diff --git a/10-constants/exercises/01/main.go b/10-constants/exercises/01-minutes-in-weeks/main.go
similarity index 95%
rename from 10-constants/exercises/01/main.go
rename to 10-constants/exercises/01-minutes-in-weeks/main.go
index d804bde..e9cf45f 100644
--- a/10-constants/exercises/01/main.go
+++ b/10-constants/exercises/01-minutes-in-weeks/main.go
@@ -8,7 +8,8 @@
 package main
 
 // ---------------------------------------------------------
-// EXERCISE
+// EXERCISE: Minutes in Weeks
+//
 //  Calculate how many minutes in two weeks.
 //
 //  STEPS:
diff --git a/10-constants/exercises/01/solution/main.go b/10-constants/exercises/01-minutes-in-weeks/solution/main.go
similarity index 100%
rename from 10-constants/exercises/01/solution/main.go
rename to 10-constants/exercises/01-minutes-in-weeks/solution/main.go
diff --git a/10-constants/exercises/02/main.go b/10-constants/exercises/02-remove-the-magic/main.go
similarity index 95%
rename from 10-constants/exercises/02/main.go
rename to 10-constants/exercises/02-remove-the-magic/main.go
index ee208f0..96c74f0 100644
--- a/10-constants/exercises/02/main.go
+++ b/10-constants/exercises/02-remove-the-magic/main.go
@@ -10,7 +10,8 @@ package main
 import "fmt"
 
 // ---------------------------------------------------------
-// EXERCISE
+// EXERCISE: Remove the Magic
+//
 //  Get rid of the magic numbers in the following code.
 //
 // RESTRICTIONS
diff --git a/10-constants/exercises/02/solution/main.go b/10-constants/exercises/02-remove-the-magic/solution/main.go
similarity index 100%
rename from 10-constants/exercises/02/solution/main.go
rename to 10-constants/exercises/02-remove-the-magic/solution/main.go
diff --git a/10-constants/exercises/03/main.go b/10-constants/exercises/03-constant-length/main.go
similarity index 96%
rename from 10-constants/exercises/03/main.go
rename to 10-constants/exercises/03-constant-length/main.go
index f3805d0..5e63332 100644
--- a/10-constants/exercises/03/main.go
+++ b/10-constants/exercises/03-constant-length/main.go
@@ -8,7 +8,8 @@
 package main
 
 // ---------------------------------------------------------
-// EXERCISE
+// EXERCISE: Constant Length
+//
 //  Calculate how many characters inside the `home`
 //  constant and print it.
 //
diff --git a/10-constants/exercises/03/solution/main.go b/10-constants/exercises/03-constant-length/solution/main.go
similarity index 100%
rename from 10-constants/exercises/03/solution/main.go
rename to 10-constants/exercises/03-constant-length/solution/main.go
diff --git a/10-constants/exercises/04/main.go b/10-constants/exercises/04-tau/main.go
similarity index 96%
rename from 10-constants/exercises/04/main.go
rename to 10-constants/exercises/04-tau/main.go
index 3fc51df..6941c12 100644
--- a/10-constants/exercises/04/main.go
+++ b/10-constants/exercises/04-tau/main.go
@@ -8,7 +8,8 @@
 package main
 
 // ---------------------------------------------------------
-// EXERCISE
+// EXERCISE: TAU
+//
 //  Fix the following program and print the TAU number.
 //
 // HINT
diff --git a/10-constants/exercises/04/solution/main.go b/10-constants/exercises/04-tau/solution/main.go
similarity index 100%
rename from 10-constants/exercises/04/solution/main.go
rename to 10-constants/exercises/04-tau/solution/main.go
diff --git a/10-constants/exercises/05/main.go b/10-constants/exercises/05-area/main.go
similarity index 96%
rename from 10-constants/exercises/05/main.go
rename to 10-constants/exercises/05-area/main.go
index ed7ec1f..bd76c85 100644
--- a/10-constants/exercises/05/main.go
+++ b/10-constants/exercises/05-area/main.go
@@ -8,7 +8,8 @@
 package main
 
 // ---------------------------------------------------------
-// EXERCISE
+// EXERCISE: Area
+//
 //  Fix the following program.
 //
 // RESTRICTION
diff --git a/10-constants/exercises/05/solution/main.go b/10-constants/exercises/05-area/solution/main.go
similarity index 100%
rename from 10-constants/exercises/05/solution/main.go
rename to 10-constants/exercises/05-area/solution/main.go
diff --git a/10-constants/exercises/06/main.go b/10-constants/exercises/06-no-conversions-allowed/main.go
similarity index 93%
rename from 10-constants/exercises/06/main.go
rename to 10-constants/exercises/06-no-conversions-allowed/main.go
index 9cdf4f8..73e1f8b 100644
--- a/10-constants/exercises/06/main.go
+++ b/10-constants/exercises/06-no-conversions-allowed/main.go
@@ -8,7 +8,8 @@
 package main
 
 // ---------------------------------------------------------
-// EXERCISE
+// EXERCISE: No Conversions Allowed
+//
 //  1. Fix the program without doing any conversion.
 //  2. Explain why it doesn't work.
 //
diff --git a/10-constants/exercises/06/solution/main.go b/10-constants/exercises/06-no-conversions-allowed/solution/main.go
similarity index 100%
rename from 10-constants/exercises/06/solution/main.go
rename to 10-constants/exercises/06-no-conversions-allowed/solution/main.go
diff --git a/10-constants/exercises/07/main.go b/10-constants/exercises/07-iota-months/main.go
similarity index 96%
rename from 10-constants/exercises/07/main.go
rename to 10-constants/exercises/07-iota-months/main.go
index e1a8b59..6e5a948 100644
--- a/10-constants/exercises/07/main.go
+++ b/10-constants/exercises/07-iota-months/main.go
@@ -10,7 +10,8 @@ package main
 import "fmt"
 
 // ---------------------------------------------------------
-// EXERCISE
+// EXERCISE: Iota Months
+//
 //  1. Initialize the constants using iota.
 //  2. You should find the correct formula for iota.
 //
diff --git a/10-constants/exercises/07/solution/main.go b/10-constants/exercises/07-iota-months/solution/main.go
similarity index 100%
rename from 10-constants/exercises/07/solution/main.go
rename to 10-constants/exercises/07-iota-months/solution/main.go
diff --git a/10-constants/exercises/08/main.go b/10-constants/exercises/08-iota-months-2/main.go
similarity index 96%
rename from 10-constants/exercises/08/main.go
rename to 10-constants/exercises/08-iota-months-2/main.go
index 3cc8bb3..7c0a1f9 100644
--- a/10-constants/exercises/08/main.go
+++ b/10-constants/exercises/08-iota-months-2/main.go
@@ -10,7 +10,8 @@ package main
 import "fmt"
 
 // ---------------------------------------------------------
-// EXERCISE
+// EXERCISE: Iota Months #2
+//
 //  1. Initialize multiple constants using iota.
 //  2. Please follow the instructions inside the code.
 //
diff --git a/10-constants/exercises/08/solution/main.go b/10-constants/exercises/08-iota-months-2/solution/main.go
similarity index 100%
rename from 10-constants/exercises/08/solution/main.go
rename to 10-constants/exercises/08-iota-months-2/solution/main.go
diff --git a/10-constants/exercises/09/main.go b/10-constants/exercises/09-iota-seasons/main.go
similarity index 89%
rename from 10-constants/exercises/09/main.go
rename to 10-constants/exercises/09-iota-seasons/main.go
index 5fc9f4a..dd0dac2 100644
--- a/10-constants/exercises/09/main.go
+++ b/10-constants/exercises/09-iota-seasons/main.go
@@ -10,8 +10,9 @@ package main
 import "fmt"
 
 // ---------------------------------------------------------
-// EXERCISE
-//  Use iota to initialize month constants.
+// EXERCISE: Iota Seasons
+//
+//  Use iota to initialize the season constants.
 //
 // HINT
 //  You can change the order of the constants.
diff --git a/10-constants/exercises/09/solution/main.go b/10-constants/exercises/09-iota-seasons/solution/main.go
similarity index 100%
rename from 10-constants/exercises/09/solution/main.go
rename to 10-constants/exercises/09-iota-seasons/solution/main.go
diff --git a/10-constants/exercises/README.md b/10-constants/exercises/README.md
new file mode 100644
index 0000000..a15af85
--- /dev/null
+++ b/10-constants/exercises/README.md
@@ -0,0 +1,20 @@
+# Constants
+
+1. **[Minutes in Weeks](https://github.com/inancgumus/learngo/tree/master/10-constants/exercises/01-minutes-in-weeks)**
+
+2. **[Remove the Magic](https://github.com/inancgumus/learngo/tree/master/10-constants/exercises/02-remove-the-magic)**
+
+3. **[Constant Length](https://github.com/inancgumus/learngo/tree/master/10-constants/exercises/03-constant-length)**
+
+4. **[TAU](https://github.com/inancgumus/learngo/tree/master/10-constants/exercises/04-tau)**
+
+5. **[Area](https://github.com/inancgumus/learngo/tree/master/10-constants/exercises/05-area)**
+
+6. **[No Conversions Allowed](https://github.com/inancgumus/learngo/tree/master/10-constants/exercises/06-no-conversions-allowed)**
+
+7. **[Iota Months](https://github.com/inancgumus/learngo/tree/master/10-constants/exercises/07-iota-months)**
+
+8. **[Iota Months #2](https://github.com/inancgumus/learngo/tree/master/10-constants/exercises/08-iota-months-2)**
+
+9. **[Iota Seasons](https://github.com/inancgumus/learngo/tree/master/10-constants/exercises/09-iota-seasons)**
+
diff --git a/11-if/exercises/01/main.go b/11-if/exercises/01/main.go
deleted file mode 100644
index cf1b0b8..0000000
--- a/11-if/exercises/01/main.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// For more tutorials: https://blog.learngoprogramming.com
-//
-// Copyright © 2018 Inanc Gumus
-// Learn Go Programming Course
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-//
-
-package main
-
-// ---------------------------------------------------------
-// EXERCISE
-//  Let's start simple. Print the expected outputs,
-//  depending on the age variable.
-//
-// EXPECTED OUTPUT
-//  If age is greater than 60, print:
-//    Getting older
-//  If age is greater than 30, print:
-//    Getting wiser
-//  If age is greater than 20, print:
-//    Adulthood
-//  If age is greater than 10, print:
-//    Young blood
-//  Otherwise, print:
-//    Booting up
-// ---------------------------------------------------------
-
-func main() {
-	// Change this accordingly to produce the expected outputs
-	// age := 10
-
-	// Type your if statement here.
-}
diff --git a/11-if/exercises/01/solution/main.go b/11-if/exercises/01/solution/main.go
deleted file mode 100644
index 80e543b..0000000
--- a/11-if/exercises/01/solution/main.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// For more tutorials: https://blog.learngoprogramming.com
-//
-// Copyright © 2018 Inanc Gumus
-// Learn Go Programming Course
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-//
-
-package main
-
-import "fmt"
-
-func main() {
-	age := 10
-
-	if age > 60 {
-		fmt.Println("Getting older")
-	} else if age > 30 {
-		fmt.Println("Getting wiser")
-	} else if age > 20 {
-		fmt.Println("Adulthood")
-	} else if age > 10 {
-		fmt.Println("Young blood")
-	} else {
-		fmt.Println("Booting up")
-	}
-}
diff --git a/11-if/exercises/02/main.go b/11-if/exercises/02/main.go
deleted file mode 100644
index 602dee2..0000000
--- a/11-if/exercises/02/main.go
+++ /dev/null
@@ -1,49 +0,0 @@
-// For more tutorials: https://blog.learngoprogramming.com
-//
-// Copyright © 2018 Inanc Gumus
-// Learn Go Programming Course
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-//
-
-package main
-
-import "fmt"
-
-// ---------------------------------------------------------
-// EXERCISE
-//  Can you simplify the if statement inside the code below?
-//
-//  When:
-//    isSphere == true and
-//    radius is equal or greater than 200
-//
-//    It will print "It's a big sphere."
-//
-//    Otherwise, it will print "I don't know."
-//
-// EXPECTED OUTPUT
-//  It's a big sphere.
-// ---------------------------------------------------------
-
-func main() {
-	// DO NOT TOUCH THIS
-	isSphere, radius := true, 100
-
-	var big bool
-
-	if radius >= 50 {
-		if radius >= 100 {
-			if radius >= 200 {
-				big = true
-			}
-		}
-	}
-
-	if big != true {
-		fmt.Println("I don't know.")
-	} else if !(isSphere == false) {
-		fmt.Println("It's a big sphere.")
-	} else {
-		fmt.Println("I don't know.")
-	}
-}
diff --git a/11-if/exercises/02/solution/main.go b/11-if/exercises/02/solution/main.go
deleted file mode 100644
index 5eb4e39..0000000
--- a/11-if/exercises/02/solution/main.go
+++ /dev/null
@@ -1,20 +0,0 @@
-// For more tutorials: https://blog.learngoprogramming.com
-//
-// Copyright © 2018 Inanc Gumus
-// Learn Go Programming Course
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-//
-
-package main
-
-import "fmt"
-
-func main() {
-	isSphere, radius := true, 200
-
-	if isSphere && radius >= 200 {
-		fmt.Println("It's a big sphere.")
-	} else {
-		fmt.Println("I don't know.")
-	}
-}
diff --git a/11-if/exercises/03/main.go b/11-if/exercises/03/main.go
deleted file mode 100644
index a4074b0..0000000
--- a/11-if/exercises/03/main.go
+++ /dev/null
@@ -1,31 +0,0 @@
-// For more tutorials: https://blog.learngoprogramming.com
-//
-// Copyright © 2018 Inanc Gumus
-// Learn Go Programming Course
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-//
-
-package main
-
-// ---------------------------------------------------------
-// EXERCISE
-//  1. Get arguments from command-line.
-//  2. Print the expected outputs below depending on the number
-//     of arguments.
-//
-// EXPECTED OUTPUT
-//  go run main.go
-//    Give me args
-//
-//  go run main.go hello
-//    There is one: "hello"
-//
-//  go run main.go hi there
-//    There are two: "hi there"
-//
-//  go run main.go i wanna be a gopher
-//    There are 5 arguments
-// ---------------------------------------------------------
-
-func main() {
-}
diff --git a/11-if/exercises/03/solution/main.go b/11-if/exercises/03/solution/main.go
deleted file mode 100644
index a69911e..0000000
--- a/11-if/exercises/03/solution/main.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// For more tutorials: https://blog.learngoprogramming.com
-//
-// Copyright © 2018 Inanc Gumus
-// Learn Go Programming Course
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-//
-
-package main
-
-import (
-	"fmt"
-	"os"
-)
-
-func main() {
-	var (
-		args = os.Args
-		l    = len(args) - 1
-	)
-
-	if l == 0 {
-		fmt.Println("Give me args")
-	} else if l == 1 {
-		fmt.Printf("There is one: %q\n", args[1])
-	} else if l == 2 {
-		fmt.Printf(
-			`There are two: "%s %s"`+"\n",
-			args[1], args[2],
-		)
-	} else {
-		fmt.Printf("There are %d arguments\n", l)
-	}
-}
diff --git a/11-if/exercises/04/main.go b/11-if/exercises/04/main.go
deleted file mode 100644
index 93d9dea..0000000
--- a/11-if/exercises/04/main.go
+++ /dev/null
@@ -1,37 +0,0 @@
-// For more tutorials: https://blog.learngoprogramming.com
-//
-// Copyright © 2018 Inanc Gumus
-// Learn Go Programming Course
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-//
-
-package main
-
-// ---------------------------------------------------------
-// EXERCISE
-//  1. Get a number from the command-line.
-//  2. Find whether the number is odd, even and divisible by 8.
-//
-// RESTRICTION
-//  Handle the error. If the number is not a valid number,
-//  or it's not provided, let the user know.
-//
-// EXPECTED OUTPUT
-//  go run main.go 16
-//    16 is an even number and it's divisible by 8
-//
-//  go run main.go 4
-//    4 is an even number
-//
-//  go run main.go 3
-//    3 is an odd number
-//
-//  go run main.go
-//    Pick a number
-//
-//  go run main.go ABC
-//    "ABC" is not a number
-// ---------------------------------------------------------
-
-func main() {
-}
diff --git a/11-if/exercises/04/solution/main.go b/11-if/exercises/04/solution/main.go
deleted file mode 100644
index 03dea19..0000000
--- a/11-if/exercises/04/solution/main.go
+++ /dev/null
@@ -1,35 +0,0 @@
-// For more tutorials: https://blog.learngoprogramming.com
-//
-// Copyright © 2018 Inanc Gumus
-// Learn Go Programming Course
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-//
-
-package main
-
-import (
-	"fmt"
-	"os"
-	"strconv"
-)
-
-func main() {
-	if len(os.Args) != 2 {
-		fmt.Println("Pick a number")
-		return
-	}
-
-	n, err := strconv.Atoi(os.Args[1])
-	if err != nil {
-		fmt.Printf("%q is not a number\n", os.Args[1])
-		return
-	}
-
-	if n%8 == 0 {
-		fmt.Printf("%d is an even number and it's divisible by 8\n", n)
-	} else if n%2 == 0 {
-		fmt.Printf("%d is an even number\n", n)
-	} else {
-		fmt.Printf("%d is an odd number\n", n)
-	}
-}
diff --git a/11-if/exercises/05/main.go b/11-if/exercises/05/main.go
deleted file mode 100644
index cf38483..0000000
--- a/11-if/exercises/05/main.go
+++ /dev/null
@@ -1,53 +0,0 @@
-// For more tutorials: https://blog.learngoprogramming.com
-//
-// Copyright © 2018 Inanc Gumus
-// Learn Go Programming Course
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-//
-
-package main
-
-// ---------------------------------------------------------
-// STORY
-//  Your boss wants you to create a program that will check
-//  whether a person can watch a particular movie or not.
-//
-//  Imagine that another program provides the age to your
-//  program. Depending on what you return, the other program
-//  will issue the tickets to the person automatically.
-//
-// EXERCISE
-//  1. Get the age from the command-line.
-//
-//  2. Return one of the following messages if the age is:
-//     -> Above 17         : "R-Rated"
-//     -> Between 13 and 17: "PG-13"
-//     -> Below 13         : "PG-Rated"
-//
-// RESTRICTIONS:
-//  1. If age data is wrong or absent let the user know.
-//  2. Do not accept negative age.
-//
-// BONUS:
-//  1. BONUS: Use if statements only twice throughout your program.
-//  2. BONUS: Use an if statement only once.
-//
-// EXPECTED OUTPUT
-//  go run main.go 18
-//    R-Rated
-//
-//  go run main.go 17
-//    PG-13
-//
-//  go run main.go 12
-//    PG-Rated
-//
-//  go run main.go
-//    Requires age
-//
-//  go run main.go -5
-//    Wrong age: "-5"
-// ---------------------------------------------------------
-
-func main() {
-}
diff --git a/11-if/exercises/05/solution/main.go b/11-if/exercises/05/solution/main.go
deleted file mode 100644
index 6aa5ebc..0000000
--- a/11-if/exercises/05/solution/main.go
+++ /dev/null
@@ -1,34 +0,0 @@
-// For more tutorials: https://blog.learngoprogramming.com
-//
-// Copyright © 2018 Inanc Gumus
-// Learn Go Programming Course
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-//
-
-package main
-
-import (
-	"fmt"
-	"os"
-	"strconv"
-)
-
-func main() {
-	if len(os.Args) != 2 {
-		fmt.Println("Requires age")
-		return
-	}
-
-	age, err := strconv.Atoi(os.Args[1])
-
-	if err != nil || age < 0 {
-		fmt.Printf(`Wrong age: %q`+"\n", os.Args[1])
-		return
-	} else if age > 17 {
-		fmt.Println("R-Rated")
-	} else if age >= 13 && age <= 17 {
-		fmt.Println("PG-13")
-	} else if age < 13 {
-		fmt.Println("PG-Rated")
-	}
-}
diff --git a/11-if/exercises/05/solution2/main.go b/11-if/exercises/05/solution2/main.go
deleted file mode 100644
index 79392d0..0000000
--- a/11-if/exercises/05/solution2/main.go
+++ /dev/null
@@ -1,34 +0,0 @@
-// For more tutorials: https://blog.learngoprogramming.com
-//
-// Copyright © 2018 Inanc Gumus
-// Learn Go Programming Course
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-//
-
-package main
-
-import (
-	"fmt"
-	"os"
-	"strconv"
-)
-
-// 🛑 DON'T DO THIS:
-//     It's hard to read.
-//     It's just an exercise.
-
-func main() {
-	if len(os.Args) != 2 {
-		fmt.Println("Requires age")
-		return
-	} else if age, err := strconv.Atoi(os.Args[1]); err != nil || age < 0 {
-		fmt.Printf(`Wrong age: %q`+"\n", os.Args[1])
-		return
-	} else if age > 17 {
-		fmt.Println("R-Rated")
-	} else if age >= 13 && age <= 17 {
-		fmt.Println("PG-13")
-	} else if age < 13 {
-		fmt.Println("PG-Rated")
-	}
-}
diff --git a/11-if/exercises/06/main.go b/11-if/exercises/06/main.go
deleted file mode 100644
index 1ff2c76..0000000
--- a/11-if/exercises/06/main.go
+++ /dev/null
@@ -1,48 +0,0 @@
-// For more tutorials: https://blog.learngoprogramming.com
-//
-// Copyright © 2018 Inanc Gumus
-// Learn Go Programming Course
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-//
-
-package main
-
-// ---------------------------------------------------------
-// EXERCISE
-//  Detect whether a letter is vowel or consonant.
-//
-// NOTE
-//  y or w is called a semi-vowel.
-//  Check out: https://en.oxforddictionaries.com/explore/is-the-letter-y-a-vowel-or-a-consonant/
-//
-// HINT
-//  + You can find the length of an argument using the len function.
-//
-//  + len(os.Args[1]) will give you the length of the 1st argument.
-//
-// BONUS
-//  Use strings.IndexAny function to detect the vowels.
-//  Search on Google for: golang pkg strings IndexAny
-//
-// EXPECTED OUTPUT
-//  go run main.go
-//    Give me a letter
-//
-//  go run main.go hey
-//    Give me a letter
-//
-//  go run main.go a
-//    "a" is a vowel.
-//
-//  go run main.go y
-//    "y" is sometimes a vowel, sometimes not.
-//
-//  go run main.go w
-//    "w" is sometimes a vowel, sometimes not.
-//
-//  go run main.go x
-//    "x" is a consonant.
-// ---------------------------------------------------------
-
-func main() {
-}
diff --git a/11-if/exercises/06/solution/main.go b/11-if/exercises/06/solution/main.go
deleted file mode 100644
index 7115aaa..0000000
--- a/11-if/exercises/06/solution/main.go
+++ /dev/null
@@ -1,34 +0,0 @@
-// For more tutorials: https://blog.learngoprogramming.com
-//
-// Copyright © 2018 Inanc Gumus
-// Learn Go Programming Course
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-//
-
-package main
-
-import (
-	"fmt"
-	"os"
-)
-
-func main() {
-	args := os.Args
-
-	if len(args) != 2 || len(args[1]) != 1 {
-		fmt.Println("Give me a letter")
-		return
-	}
-
-	// I didn't use a short-if here because, it's already
-	// hard to read. Do not make it harder.
-
-	s := args[1]
-	if s == "a" || s == "e" || s == "i" || s == "o" || s == "u" {
-		fmt.Printf("%q is a vowel.\n", s)
-	} else if s == "w" || s == "y" {
-		fmt.Printf("%q is sometimes a vowel, sometimes not.\n", s)
-	} else {
-		fmt.Printf("%q is a consonant.\n", s)
-	}
-}
diff --git a/11-if/exercises/06/solution2/main.go b/11-if/exercises/06/solution2/main.go
deleted file mode 100644
index fe714df..0000000
--- a/11-if/exercises/06/solution2/main.go
+++ /dev/null
@@ -1,39 +0,0 @@
-// For more tutorials: https://blog.learngoprogramming.com
-//
-// Copyright © 2018 Inanc Gumus
-// Learn Go Programming Course
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-//
-
-package main
-
-import (
-	"fmt"
-	"os"
-	"strings"
-)
-
-func main() {
-	args := os.Args
-
-	if len(args) != 2 || len(args[1]) != 1 {
-		fmt.Println("Give me a letter")
-		return
-	}
-
-	s := args[1]
-	if strings.IndexAny(s, "aeiou") != -1 {
-		fmt.Printf("%q is a vowel.\n", s)
-	} else if s == "w" || s == "y" {
-		fmt.Printf("%q is sometimes a vowel, sometimes not.\n", s)
-	} else {
-		fmt.Printf("%q is a consonant.\n", s)
-	}
-
-	// Notice that:
-	//
-	// I didn't use IndexAny for the else if above.
-	//
-	// It's because, calling a function is a costly operation.
-	// And, this way, the code is simpler.
-}
diff --git a/11-if/exercises/07/main.go b/11-if/exercises/07/main.go
deleted file mode 100644
index 0232081..0000000
--- a/11-if/exercises/07/main.go
+++ /dev/null
@@ -1,35 +0,0 @@
-// For more tutorials: https://blog.learngoprogramming.com
-//
-// Copyright © 2018 Inanc Gumus
-// Learn Go Programming Course
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-//
-
-package main
-
-// ---------------------------------------------------------
-// EXERCISE
-//  Find out whether a given year is a leap year or not.
-//
-// EXPECTED OUTPUT
-//  go run main.go
-//    Give me a year number
-//
-//  go run main.go eighties
-//    "eighties" is not a valid year.
-//
-//  go run main.go 2018
-//    2018 is not a leap year.
-//
-//  go run main.go 2019
-//    2019 is not a leap year.
-//
-//  go run main.go 2020
-//    2020 is a leap year.
-//
-//  go run main.go 2024
-//    2024 is a leap year.
-// ---------------------------------------------------------
-
-func main() {
-}
diff --git a/11-if/exercises/07/solution/main.go b/11-if/exercises/07/solution/main.go
deleted file mode 100644
index fa0c780..0000000
--- a/11-if/exercises/07/solution/main.go
+++ /dev/null
@@ -1,46 +0,0 @@
-// For more tutorials: https://blog.learngoprogramming.com
-//
-// Copyright © 2018 Inanc Gumus
-// Learn Go Programming Course
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-//
-
-package main
-
-import (
-	"fmt"
-	"os"
-	"strconv"
-)
-
-func main() {
-	if len(os.Args) != 2 {
-		fmt.Println("Give me a year number")
-		return
-	}
-
-	year, err := strconv.Atoi(os.Args[1])
-	if err != nil {
-		fmt.Printf("%q is not a valid year.\n", os.Args[1])
-		return
-	}
-
-	// Notice that:
-	// I've intentionally created this solution as verbose
-	// as I can.
-	//
-	// See the next exercise.
-
-	var leap bool
-	if year%400 == 0 {
-		leap = true
-	} else if year%4 == 0 {
-		leap = true
-	}
-
-	if leap {
-		fmt.Printf("%d is a leap year.\n", year)
-	} else {
-		fmt.Printf("%d is not a leap year.\n", year)
-	}
-}
diff --git a/11-if/exercises/08/main.go b/11-if/exercises/08/main.go
deleted file mode 100644
index cc97d78..0000000
--- a/11-if/exercises/08/main.go
+++ /dev/null
@@ -1,20 +0,0 @@
-// For more tutorials: https://blog.learngoprogramming.com
-//
-// Copyright © 2018 Inanc Gumus
-// Learn Go Programming Course
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-//
-
-package main
-
-// ---------------------------------------------------------
-// EXERCISE
-//  1. Look at the solution of "the previous exercise".
-//  2. And simplify the code (especially the if statements!).
-//
-// EXPECTED OUTPUT
-//  It's the same as the previous exercise.
-// ---------------------------------------------------------
-
-func main() {
-}
diff --git a/11-if/exercises/08/solution/main.go b/11-if/exercises/08/solution/main.go
deleted file mode 100644
index 7c6c018..0000000
--- a/11-if/exercises/08/solution/main.go
+++ /dev/null
@@ -1,36 +0,0 @@
-// For more tutorials: https://blog.learngoprogramming.com
-//
-// Copyright © 2018 Inanc Gumus
-// Learn Go Programming Course
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-//
-
-package main
-
-import (
-	"fmt"
-	"os"
-	"strconv"
-)
-
-func main() {
-	if len(os.Args) != 2 {
-		fmt.Println("Give me a year number")
-		return
-	}
-
-	year, err := strconv.Atoi(os.Args[1])
-	if err != nil {
-		fmt.Printf("%q is not a valid year.\n", os.Args[1])
-		return
-	}
-
-	if year%4 == 0 && (year%100 != 0 || year%400 == 0) {
-		fmt.Printf("%d is a leap year.\n", year)
-	} else {
-		fmt.Printf("%d is not a leap year.\n", year)
-	}
-}
-
-// Review the original source code here:
-// https://github.com/golang/go/blob/ad644d2e86bab85787879d41c2d2aebbd7c57db8/src/time/time.go#L1289
diff --git a/11-if/exercises/09/main.go b/11-if/exercises/09/main.go
deleted file mode 100644
index 8ad76de..0000000
--- a/11-if/exercises/09/main.go
+++ /dev/null
@@ -1,89 +0,0 @@
-// For more tutorials: https://blog.learngoprogramming.com
-//
-// Copyright © 2018 Inanc Gumus
-// Learn Go Programming Course
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-//
-
-package main
-
-// ---------------------------------------------------------
-// EXERCISE
-//  Print the number of days in a given month.
-//
-// RESTRICTIONS
-//  1. On a leap year, february should print 29. Otherwise, 28.
-//
-//     Set your computer clock to 2020 to see whether it works.
-//
-//  2. It should work case-insensitive. See below.
-//
-//     Search on Google: golang pkg strings ToLower
-//
-//  3. Get the current year using the time.Now()
-//
-//     Search on Google: golang pkg time now year
-//
-//
-// EXPECTED OUTPUT
-//
-//  -----------------------------------------
-//  Your solution should not accept invalid months
-//  -----------------------------------------
-//  go run main.go
-//    Give me a month name
-//
-//  go run main.go sheep
-//    "sheep" is not a month.
-//
-//  go run main.go january
-//    "january" has 31 days.
-//
-//  -----------------------------------------
-//  Your solution should handle the leap years
-//  -----------------------------------------
-//  go run main.go february
-//    "february" has 28 days.
-//
-//  go run main.go march
-//    "march" has 31 days.
-//
-//  go run main.go april
-//    "april" has 30 days.
-//
-//  go run main.go may
-//    "may" has 31 days.
-//
-//  go run main.go june
-//    "june" has 30 days.
-//
-//  go run main.go july
-//    "july" has 31 days.
-//
-//  go run main.go august
-//    "august" has 31 days.
-//
-//  go run main.go september
-//    "september" has 30 days.
-//
-//  go run main.go october
-//    "october" has 31 days.
-//
-//  go run main.go november
-//    "november" has 30 days.
-//
-//  go run main.go december
-//    "december" has 31 days.
-//
-//  -----------------------------------------
-//  Your solution should be case insensitive
-//  -----------------------------------------
-//  go run main.go DECEMBER
-//    "DECEMBER" has 31 days.
-//
-//  go run main.go dEcEmBeR
-//    "dEcEmBeR" has 31 days.
-// ---------------------------------------------------------
-
-func main() {
-}
diff --git a/11-if/exercises/09/solution/main.go b/11-if/exercises/09/solution/main.go
deleted file mode 100644
index e51ee9f..0000000
--- a/11-if/exercises/09/solution/main.go
+++ /dev/null
@@ -1,58 +0,0 @@
-// For more tutorials: https://blog.learngoprogramming.com
-//
-// Copyright © 2018 Inanc Gumus
-// Learn Go Programming Course
-// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
-//
-
-package main
-
-import (
-	"fmt"
-	"os"
-	"strings"
-	"time"
-)
-
-func main() {
-	if len(os.Args) != 2 {
-		fmt.Println("Give me a month name")
-		return
-	}
-
-	// get the current year and find out whether it's a leap year
-	year := time.Now().Year()
-	leap := year%4 == 0 && (year%100 != 0 || year%400 == 0)
-
-	// setting it to 28, saves me typing it below again
-	days := 28
-
-	month := os.Args[1]
-
-	// case insensitive
-	if m := strings.ToLower(month); m == "april" ||
-		m == "june" ||
-		m == "september" ||
-		m == "november" {
-		days = 30
-	} else if m == "january" ||
-		m == "march" ||
-		m == "may" ||
-		m == "july" ||
-		m == "august" ||
-		m == "october" ||
-		m == "december" {
-		days = 31
-	} else if m == "february" {
-		// try a "logical and operator" above.
-		// like: `else if m == "february" && leap`
-		if leap {
-			days = 29
-		}
-	} else {
-		fmt.Printf("%q is not a month.\n", month)
-		return
-	}
-
-	fmt.Printf("%q has %d days.\n", month, days)
-}