IF 1 = 2, 4 = 20, 6 = 42, 9 = 90 Then 10 =?

Question

If:

2=6     
3=12
4=20
5=30
6=42

Then

9= ??

Answer 1

1 = 1*2 i.e. 2
4 = 4*5 i.e. 20
6 = 6*7 i.e. 42
9 = 9*10 i.e. 90
10 = 10*11 i.e. 110

Answer 2

answer is 110
n*(n+1)
10*11=110