Arithmetic eXtensions for Ruby

Ruby should have rich and exact Arithmetic. Let's improve it.

Math

• .integer_length
• .digit_count
• .range_product
• .factorial
• .binomial_coefficient
• .multinomial_coefficient

Numeric

• plus?
• minus?
• positive?
• negative?
• non_positive?
• non_zero?
• half
• double
• square
• cube