Attempt to implement the "math hack" described here: http://9gag.com/gag/6663551 WiP, this is just a quick kludge and doesn't work 100% yet.

math_hack.rb

#99 x 99 = 9312 |

def reset
  "\e[0m"
end

def mult l, r
  lb = 10 ** l.to_s.size
  rb = 10 ** r.to_s.size

  ls = lb - l
  rs = rb - r

  sig = [lb, rb].max - (ls + rs)
  ins = ls * rs

  ins = "#{('0' * (rb.to_s.size - ins.to_s.size - 1))}#{ins}" if ins.to_s.length < rb.to_s.size

  "#{sig}#{ins}".to_i
end

def display lnumber, rnumber, result
  color = result == lnumber * rnumber ? "\e[32m" : "\e[31m"

  print "#{color}#{lnumber}x#{rnumber} = #{result}"
  print "#{reset} | "
end

def test
  lnum = 97
  rnum = 96

  result = mult lnum, rnum

  display lnum, rnum, result

  puts
  exit
end

def test_loop
  100.times do |lnumber|
    100.times do |rnumber|
      result = mult lnumber, rnumber

      display lnumber, rnumber, result
    end
  end

  puts
end

test_loop

def math_hack(a,b)
  c = 100 -a
  d = 100 -b
  r1 = 100 - c - d
  r2 = c * d
  r1 * 100 + r2
end

(1..100).map do |i|
  (1..100).map do |j|
    i*j - math_hack(i,j)
  end
end.flatten.all?{|i| i == 0}