Combinations in A level ?

In A level mathematics, combinations refer to the number of ways in which a selection of items can be made without regard to the order in which they are selected. The formula for combinations is given by:

nCr = n! / r!(n-r)!

Where n is the total number of items, r is the number of items being selected, and ! denotes the factorial function.

Combinations are often used in probability and statistics to calculate the number of possible outcomes in a given scenario. They are also used in combinatorics to solve problems involving arrangements and selections of objects.