Q; How many ways can 20 people be divided into 4 equal groups?

Question

1. How many ways can 20 people be divided into 4 equal groups?

The answer is 1.17 x 10¹⁰, what's the reason to this? Please show the steps.

Answer 1

Four equal groups means 5 people in each group.

The order of the people within the group does not matter, therefore use combination.

₂₀C₅ = ?

I get 15,504.

1.17 x 10¹⁰ = 11,700,000,000. Slightly excessive.