Question

6 , 12 , 20 , 30 , 42 , 56 , 72 , . . .

Answer 1

The next number would be 90.

Explanation: 6+6=12
12+8=20
20+10=30
30+12=42
42+14=56
56+16=72

You keep adding two every time. So you would then do 72+18=90.

Hope this helps! :)