sample ruby-double

double.rb

# double the number
def double(x)
  x * 2
end

double(2) # => 4
double(3) # => 6
double(4) # => 8

# squares the number
def square(x)
  x * x
end

square(2) # => 4
square(3) # => 9
square(4) # => 16