Direction In each series, look for the degree and direction of change between the numbers. In other words, do the numbers increase or decrease, and by how much-
6.

Look at this series: 21, 9, 21, 11, 21, 13, 21, ... What number should come next?
A. 14
 B. 15
C. 21
 D. 23
Answer and Explanation
Answer: B

Explanation: In this alternating repetition series, the random number 21 is interpolated every other number into an otherwise simple addition series that increases by 2, beginning with the number 9.




7.

Look at this series: 58, 52, 46, 40, 34, ... What number should come next?
A. 26
 B. 28
C. 30
 D. 32
Answer and Explanation
Answer: B

Explanation: This is a simple subtraction series. Each number is 6 less than the previous number.




8.

Look at this series: 3, 4, 7, 8, 11, 12, ... What number should come next?
A. 7
 B. 10
C. 14
 D. 15
Answer and Explanation
Answer: D

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




9.

Look at this series: 8, 22, 8, 28, 8, ... What number should come next?
A. 9
 B. 29
C. 32
 D. 34
Answer and Explanation
Answer: D

Explanation: This is a simple addition series with a random number, 8, interpolated as every other number. In the series, 6 is added to each number except 8, to arrive at the next number.




10.

Look at this series: 31, 29, 24, 22, 17, ... What number should come next?
A. 15
 B. 14
C. 13
 D. 12
Answer and Explanation
Answer: A

Explanation: This is a simple alternating subtraction series, which subtracts 2, then 5.