Look at this series: 70, 71, 76, __, 81, 86, 70, 91, ... What number should fill the blank?

This is a simple addition series; each number is 3 more than the previous number.

This is an alternating division and addition series: First, divide by 2, and then add 8.

The letters decrease by 1; the numbers are multiplied by 2.

This is a simple addition series with repetition. It adds 3 to each number to arrive at the next, which is repeated before 3 is added again.

Two patterns alternate here. The first pattern begins with 10 and adds 2 to each number to arrive at the next; the alternating pattern begins with 34 and subtracts 3 each time.

This is a simple alternating addition and subtraction series. The first series begins with 8 and adds 3; the second begins with 43 and subtracts 2.

This is an alternating addition and subtraction series. Roman numbers alternate with Arabic numbers. In the Roman numeral pattern, each number decreases by 1. In the Arabic numeral pattern, each number increases by 1.

This is a multiplication series; each number is 3 times the previous number.

This is a simple subtraction series in which a random number, 93, is interpolated as every third number. In the subtraction series, 10 is subtracted from each number to arrive at the next.

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.