Question

0,2,6,?,20,30,42 find the mising no.

Answer 1

subtract each term by its next term .......you will get a series like this .....
2 ,4,?,8,10,12
where difference of each consecutive term is constant i.e. 2
hence above series is an AP
by using formula of nth term we get the required term as 6.
Now add the 6 in previous term of given series
6+6=12
hence 12 is the answer.