Because there are duplicate values in direct calculation, it needs to be subtracted. For example, when calculating the number of people between Xiaohong and Xiaoming, neither Xiaohong's position nor Xiaoming's position can be included. Usually it is the result of Xiao Ming's position MINUS Xiao Hong's position. This result does not contain Xiaohong's position, but contains Xiaoming's position, so we need to subtract Xiaoming's position.

Regarding the queuing problem, the simplest way to do the problem is to draw lots, but this method of drawing lots is only applicable to fill-in-the-blank questions, true and false questions, etc. If you encounter the queuing problem of application problems, you need column calculation, and drawing is not applicable.

Some skills of queuing:

The problem-solving skills of these three types of problems also have corresponding formulas:

For example, the first question is "3 people in front and 4 people in the back", and the formula is "front+back+1= total number of people".

The second question is "Top 4 and Back 3", and the formula is "Front+Back-1= total number of people".

The third question is "from the back row to the fourth row, there are three people behind", and the formula for doing the question is "before+after = total number of people".