What is the missing number in the series: 2, 6, 12, 20, ?, 42

B. 32

What is the missing number in the series: 10, 20, 40, 80, ?, 320

A. 160

A, E, I, M, ?

A. O

Find the missing letter in the series: M, O, Q, S, ?

A. T

Complete the series: m, n, p, q, ?

A. R