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

B. 32

Find the missing number in the series: 5, 11, 23, 47, ?, 191

C. 97

What number should replace the question mark in the series: 1, 4, 9, 16, ?, 36

A. 25

Identify the missing number in the series: 3, 7, 15, 31, ?, 127

A. 63

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

A. 160