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

At first you may get confused but look at those numbers carefully :)

as you see first result is divisible buy one of the product (second product in all cases is unknown)
so let's check where it will lead us :)











Now you can clearly see that every number was multiplied by number 1 higher than itself. 






etc...

it means that after equation sign there should be because 

:)