add: numbers and strings exercises

08-numbers-and-strings/01-numbers/exercises/08-sphere-area/solution/main.go

@@ -0,0 +1,26 @@
+// 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"
+	"math"
+	"os"
+	"strconv"
+)
+
+func main() {
+	var radius, area float64
+
+	radius, _ = strconv.ParseFloat(os.Args[1], 64)
+
+	area = 4 * math.Pi * math.Pow(radius, 2)
+
+	fmt.Printf("radius: %g -> area: %.2f\n",
+		radius, area)
+}