# How many ways can 6 cars line up for a race?

The first space, all 6 cars could line up here. The second space only 5 could line up here as one of them occupies the first space. This carries on until you come to the last space. With lists like this we use factorials. Our answer would be 6!=$6 \times 5 \times 4 \times 3 \times 2 \times 1$