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

A. 8

In the series X, Y, ?, A, B, what character is missing?

A. Z

What character should replace the question mark in the sequence A, B, C, ?, E?

A. D

What character should be inserted in the following pattern: 2, 4, 8, ?, 32?

A. 16

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

A. E