What number should come next in the series: 3, 6, 11, 18, ?

A. 25

Find the missing number in the series: 5, 10, 20, 40, ?, 160.

C. 80

What number should replace the question mark in the series: 3, 8, 15, 24, ?, 60

B. 36

What is the missing number in the series: 100, 90, 80, 70, ?

A. 60

What number should replace the question mark in the series: 1, 1, 2, 3, 5, ?

B. 7