If 2 = 6, 3 = 12, 4 = 20, 5 = 30, 6 = 42 then 9 = ?

2 * 3 = 6

3 * 4 = 12

4 * 5 = 20

5 * 6 = 30

6 * 7 = 42

7 * 8 = 56

8 * 9 = 72

9 * 10 = 90

The answer is 90 because I notice that in each number it is multiplied by a number that is increased by 1 in order to make sure it is equal.