Number methods in Ruby
Ruby provides a variety of built-in methods you may use on numbers. The following is an incomplete list of integer and float methods.
Even:
Use .even?
to check whether or not an integer is even. Returns a true
or false
boolean.
15.even? #=> false
4.even? #=> true
Odd:
Use .odd?
to check whether or not an integer is odd. Returns a true
or false
boolean.
15.odd? #=> true
4.odd? #=> false
Ceil:
The .ceil
method rounds floats up to the nearest number. Returns an integer.
8.3.ceil #=> 9
6.7.ceil #=> 7
Floor:
The .floor
method rounds floats down to the nearest number. Returns an integer.
8.3.floor #=> 8
6.7.floor #=> 6
Next:
Use .next
to return the next consecutive integer.
15.next #=> 16
2.next #=> 3
-4.next #=> -3
Pred:
Use .pred
to return the previous consecutive integer.
15.pred #=> 14
2.pred #=> 1
(-4).pred #=> -5
To String:
Using .to_s
on a number (integer, floats, etc.) returns a string of that number.
15.to_s #=> "15"
3.4.to_s #=> "3.4"
Greatest Common Denominator:
The .gcd
method provides the greatest common divisor (always positive) of two numbers. Returns an integer.
15.gcd(5) #=> 5
3.gcd(-7) #=> 1
Round:
Use .round
to return a rounded integer or float.
1.round #=> 1
1.round(2) #=> 1.0
15.round(-1) #=> 20
Times:
Use .times
to iterate the given block int
times.
5.times do |i|
print i, " "
end
#=> 0 1 2 3 4
Math operations in Ruby
In Ruby you can perform all standard math operations on numbers, including: addition +
, subtraction -
, multiplication *
, division /
, find remainders %
, and work with exponents **
.
Addition:
Numbers can be added together using the +
operator.
15 + 25 #=> 40
Subtraction:
Numbers can be subtracted from one another using the -
operator.
25 - 15 #=> 10
Multiplication:
Numbers can be multiplied together using the *
operator.
10 * 5 #=> 50
Division:
Numbers can be divided by one another using the /
operator.
10 / 5 #=> 2
Remainders:
Remainders can be found using the modulus %
operator.
10 % 3 #=> 1 # because the remainder of 10/3 is 1
Exponents:
Exponents can be calculated using the **
operator.
2 ** 3 #=> 8 # because 2 to the third power, or 2 * 2 * 2 = 8