106 lines
4.6 KiB
Markdown
106 lines
4.6 KiB
Markdown
---
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title: Ruby Number Methods
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---
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Ruby provides a variety of built-in methods you may use on numbers. The following is an incomplete list of <a href='https://ruby-doc.org/core-2.2.0/Integer.html' target='_blank' rel='nofollow'>integer</a> and <a href='https://ruby-doc.org/core-2.2.0/Float.html#method-i-ceil' target='_blank' rel='nofollow'>float</a> methods.
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## <a href='https://ruby-doc.org/core-2.2.0/Integer.html#method-i-even-3F' target='_blank' rel='nofollow'>Even</a>:
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Use `.even?` to check whether or not an <a href='https://ruby-doc.org/core-2.2.0/Integer.html' target='_blank' rel='nofollow'>**integer**</a> is even. Returns a `true` or `false` **boolean**.
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```Ruby
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15.even? #=> false
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4.even? #=> true
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```
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## <a href='https://ruby-doc.org/core-2.2.0/Integer.html#method-i-odd-3F' target='_blank' rel='nofollow'>Odd</a>:
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Use `.odd?` to check whether or not an <a href='https://ruby-doc.org/core-2.2.0/Integer.html' target='_blank' rel='nofollow'>**integer**</a> is odd. Returns a `true` or `false` **boolean**.
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```Ruby
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15.odd? #=> true
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4.odd? #=> false
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```
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## <a href='https://ruby-doc.org/core-2.2.0/Float.html#method-i-ceil' target='_blank' rel='nofollow'>Ceil</a>:
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The `.ceil` method rounds <a href='https://ruby-doc.org/core-2.2.0/Float.html#method-i-ceil' target='_blank' rel='nofollow'>**floats**</a> **up** to the nearest number. Returns an <a href='https://ruby-doc.org/core-2.2.0/Integer.html' target='_blank' rel='nofollow'>**integer**</a>.
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```Ruby
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8.3.ceil #=> 9
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6.7.ceil #=> 7
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```
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## <a href='https://ruby-doc.org/core-2.2.0/Float.html#method-i-floor' target='_blank' rel='nofollow'>Floor</a>:
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The `.floor` method rounds <a href='https://ruby-doc.org/core-2.2.0/Float.html#method-i-ceil' target='_blank' rel='nofollow'>**floats**</a> **down** to the nearest number. Returns an <a href='https://ruby-doc.org/core-2.2.0/Integer.html' target='_blank' rel='nofollow'>**integer**</a>.
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```Ruby
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8.3.floor #=> 8
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6.7.floor #=> 6
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```
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## <a href='https://ruby-doc.org/core-2.2.0/Integer.html#method-i-next' target='_blank' rel='nofollow'>Next</a>:
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Use `.next` to return the next consecutive <a href='https://ruby-doc.org/core-2.2.0/Integer.html' target='_blank' rel='nofollow'>**integer**</a>.
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```Ruby
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15.next #=> 16
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2.next #=> 3
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-4.next #=> -3
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```
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## <a href='https://ruby-doc.org/core-1.8.7/Integer.html#method-i-pred' target='_blank' rel='nofollow'>Pred</a>:
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Use `.pred` to return the previous consecutive <a href='https://ruby-doc.org/core-2.2.0/Integer.html' target='_blank' rel='nofollow'>**integer**</a>.
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```Ruby
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15.pred #=> 14
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2.pred #=> 1
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(-4).pred #=> -5
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```
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## <a href='https://ruby-doc.org/core-2.4.2/Object.html#method-i-to_s' target='_blank' rel='nofollow'>To String</a>:
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Using `.to_s` on a number (<a href='https://ruby-doc.org/core-2.2.0/Integer.html' target='_blank' rel='nofollow'>**integer**</a>, <a href='https://ruby-doc.org/core-2.2.0/Float.html#method-i-ceil' target='_blank' rel='nofollow'>**floats**</a>, etc.) returns a <a href='https://ruby-doc.org/core-2.2.0/String.html' target='_blank' rel='nofollow'>string</a> of that number.
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```Ruby
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15.to_s #=> "15"
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3.4.to_s #=> "3.4"
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```
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## <a href='https://ruby-doc.org/core-2.5.3/Integer.html#method-i-to_f' target='_blank' rel='nofollow'>To Float</a>:
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Converts an Integer to a Float.
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```Ruby
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15.to_f #=> 15.0
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```
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## <a href='https://ruby-doc.org/core-2.5.3/Integer.html#method-i-abs' target='_blank' rel='nofollow'>Absolute value</a>:
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Returns the absolute value of the integer.
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```Ruby
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-12345.abs #=> 12345
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12345.abs #=> 12345
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```
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## <a href='https://ruby-doc.org/core-2.2.0/Integer.html#method-i-gcd' target='_blank' rel='nofollow'>Greatest Common Denominator</a>:
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The `.gcd` method provides the greatest common divisor (always positive) of two numbers. Returns an <a href='https://ruby-doc.org/core-2.2.0/Integer.html' target='_blank' rel='nofollow'>**integer**</a>.
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```Ruby
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15.gcd(5) #=> 5
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3.gcd(-7) #=> 1
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```
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## <a href='http://ruby-doc.org/core-2.2.0/Integer.html#method-i-round' target='_blank' rel='nofollow'>Round</a>:
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Use `.round` to return a rounded <a href='https://ruby-doc.org/core-2.2.0/Integer.html' target='_blank' rel='nofollow'>**integer**</a> or <a href='https://ruby-doc.org/core-2.2.0/Float.html' target='_blank' rel='nofollow'>**float**</a>.
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```Ruby
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1.round #=> 1
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1.round(2) #=> 1.0
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15.round(-1) #=> 20
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```
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## <a href='http://ruby-doc.org/core-2.2.0/Integer.html#method-i-times' target='_blank' rel='nofollow'>Times</a>:
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Use `.times` to iterate the given block ```int``` times.
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```Ruby
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5.times do |i|
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print i, " "
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end
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#=> 0 1 2 3 4
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```
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