Generally, in the absence of sorting, the combination method, namely C (5 5,3), is adopted, and the calculation method is as follows:

C(5，3)= 5x4x 3/3x2x 1 = 60/6 = 10

The primary school is like this: mark five people as 1, 2, 3, 4, 5; There are too many ways to choose three people to form a group (regardless of sorting):123; 124; 125; 134; 135; 145; 234; 235; 245; 345;