Always compromise on quantity, compare the size with the quantity needed, and always narrow down the scope to find it. This is the dichotomy.

Example: 123456789 Find a number.

Take 5 for the first time and compare it with the required number. If the required number is greater than 5, take 5-9.

Then take 7 from 5-9 and compare it with the required number. If so, the required quantity is 7, but it is not. . Less than 7 is 6, and greater than 7 is 8.