1000+ Difficult Mathematical Puzzles with Solutions - 1

Ans: D

This is an alternating addition series with a random number, 4 interpolated as every third number. In the main series, 1 is added, then 2 is added, then 1, then 2, and so on.

Ans: A

This is an alternating subtraction series with the interpolation of a random number, 5, as every third number. In the subtraction series, 3 is subtracted, then 4, then 3, and so on.

Ans: D

Here, there are two alternating patterns, with every other number following a different pattern. The first pattern begins with 13 and adds 2 to each number to arrive at the next; the alternating pattern begins with 29 and subtracts 3 each time.

Ans: B

This is a simple subtraction series in which a random number, 85, is interpolated as every third number. In the subtraction series, 10 is subtracted from each number to arrive at the next.

Ans: 15

This alternating addition series begins with 3; then 1 is added to give 4; then 3 is added to give 7; then 1 added and so on.