Question

1, 3, 3, 6, 7, 9, ? 12, 21, 15


solve this no. series​

Answer 1

Answer:

Clearly, the given sequence is a combination of two series :

I, 3, 7, ?, 21 and

II. 3, 6, 9, 12

The pattern followed in I is + 2, + 4, + 6, ..and the pattern followed in II is + 3.

So, missing number = 7+ 6 = 13.