There are several math problems between two people. If there is no one between two people, there are only 0 people. If there are people in the middle, it is necessary to know the conditions for one person to rank and the other person to calculate the number of people between them. This problem is actually addition and subtraction.

Students lined up to get on the bus. Xiaohong ranked eighth, Xiao Qiang ranked 12, and there were several people between Xiaohong and Xiao Qiang.

12-8- 1

=4- 1

=3 (person)

There are three people between Xiaohong and Xiao Qiang.

Law of addition:

Addition has several important properties. It is interchangeable, which means that the order is not important, it is interrelated, which means that when more than two numbers are added, the order in which the addition is performed is not important. Repeated addition 1 is the same as counting, adding 0 does not change the result, and addition also follows related operations (such as subtraction and multiplication).

Addition is one of the simplest numerical tasks and the most basic addition: 1+ 1, five-month-old babies and even other animal species can be calculated. In primary education, students are taught to calculate the superposition of decimal numbers, starting with one digit, and gradually solving the difficult numerical calculation.