Permutation vs. Combination vs. Factorial

Front

What is a permutation?

Back

A permutation is an arrangement of objects in a specific order. The number of permutations of n objects taken r at a time is given by the formula: nPr = n! / (n - r)!.

Front

What is a combination?

Back

A combination is a selection of objects without regard to the order. The number of combinations of n objects taken r at a time is given by the formula: nCr = n! / (r! * (n - r)!).

Front

What is a factorial?

Back

A factorial, denoted as n!, is the product of all positive integers up to n. For example, 5! = 5 × 4 × 3 × 2 × 1 = 120.

Front

Calculate 52P3.

Back

132600

Front

Calculate 25C1.

Back

25

Front

Calculate 20C18.

Back

190

Front

Calculate 20P2.

Back

380

Front

Calculate 7!.

Back

5040

Front

What is the difference between permutation and combination?

Back

The main difference is that permutations consider the order of selection, while combinations do not.

Front

When would you use combinations instead of permutations?

Back

Use combinations when the order of selection does not matter, such as in a lottery or choosing team members.