Here's a basic example of using Ruby to create a class with destructive methods. Though this is not as practical as just typing the actual mathematic operations themselves. It does illustrate how destructive functions work and how to write them. Note the 'return self' in each of the destructive methods. This allows you to perform the method chains, without it the method returns a fixnum by default and the method chaining raises an error. If anyone knows of a DRY way to perform this let me know.
class Calculator def initialize(value) @value = value end def multiply!(value) @value *= value return self end def add!(value) @value += value return self end def clear! @value = 0 return self end def calculate puts @value end end c = Calculator.new(10) c.add!(2).multiply!(4).calculate #=> 48 c.clear!.add!(5).multiply!(4).calculate #=> 20