In the series: 1, 4, 9, ?, 25, what number should replace the question mark?

A. 16

In the sequence A, B, C, D, ?, F, G, what character should replace the question mark?

A. E

In the sequence 3, 6, 9, ?, 15, 18, what number should replace the question mark?

B. 12

If the pattern is M, N, O, ?, Q, R, what character should replace the question mark?

A. P

If the pattern is 1, 2, 4, ?, 16, what number should replace the question mark?

B. 8