8 12 9 13 10 14 11

This simple addition series adds 4 to each number to arrive at the next.

This is an alternating subtraction series in which 2 is subtracted twice, then 3 is subtracted once, then 2 is subtracted twice, and so on.

This is an alternating addition series, in which 10 is added, then 5, then 10, and so on.

Here, every other number follows a different pattern. In the first series, 6 is added to each number to arrive at the next. In the second series, 10 is added to each number to arrive at the next.

This is a subtraction series with repetition. Each number repeats itself and then decreases by 9.

This is an alternating subtraction series, which subtracts 5, then 2, then 5, and so on.

This is an alternating addition series, with a random number, 35, interpolated as every third number. The pattern of addition is to add 2, add 5, add 2, and so on. The number 35 comes after each "add 2" step/

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.

In this simple addition with repetition series, each number in the series repeats itself, and then increases by 12 to arrive at the next number.

This is a simple subtraction series, in which 3 is subtracted from each number to arrive at the next.