ruby - Calculating with Functions

=begin
kata:
http://www.codewars.com/kata/calculating-with-functions/

Description:

This time we want to write calculations using functions and get the results. Let's have a look at some examples:

seven(times(five)) # must return 35
four(plus(nine)) # must return 13
eight(minus(three)) # must return 5
six(divided_by(two)) # must return 3
=end

#Solution

def match number, string=nil
  unless string.nil?
    return eval( number.to_s + string.to_s )
  end
  number
end

def zero function=nil
  match(0, function)
end
def one function=nil
  match(1, function)
end
def two function=nil
  match(2, function)
end
def three function=nil
  match(3, function)
end
def four function=nil
  match(4, function)
end
def five function=nil
  match(5, function)
end
def six function=nil
  match(6, function)
end
def seven function=nil
  match(7, function)
end
def eight function=nil
  match(8, function)
end
def nine function=nil
  match(9, function)
end

def plus number=nil
  "+ "+number.to_s
end
def minus number=nil
  "- "+number.to_s
end
def times number=nil
  "* "+number.to_s
end
def divided_by number=nil
  return " / "+number.to_s+".0"
end