Classic example: Han Xin ordered three soldiers to walk seventy, five trees and twenty-one sticks, and seven members to practice in groups for half a month before dividing by one hundred and five.

If you ask this question,

This problem can be considered as follows: a group of four people lacks three, and a group of five people lacks three. So we found the same point. The number of apples is a multiple of 4 and 5, which is 3. That is, at least 17 and at most 37 and 57. ...