The definition and calculation formula of combination: from n different elements, any m(m≤n) elements are grouped, which is called the combination of m elements of n different elements; The number of all combinations of m(m≤n) elements from n different elements is called the number of combinations of m elements from n different elements. Represented by the symbol C(n, m). C(n,m)=A(n,m)/m! Where m! Represents the factorial of m, m! = m * (m-1) (m-2) ...1,I hope I can help you.