If Andrew is thinking of a number less then 52 and greater then 40, his number has 3 ones. What's the answer?

Answer 1

The number has a "3" in the ones place: 3, 13, 23, 33 . . .

SInce it's less than 52, it can't be 53 or higher. Since it's greater than 40, it can't be 33 or lower. It has to be 43.