Numbers x and y don't end with a digit 0. Their multiplication is 10,000. What does x+y equal to?
10,000= 2x5x2x5x2x5x2x5. Don't put any of the twos or fives together or you'll get a number ending in zero. Must be 2x2x2x2 mult by 5x5x5x5=. 16 x 625. Now add them up.