### Number Series

2, 1, (1/2), (1/4), ?

(1/3)

(1/8)

(2/8)

(1/16)

each number is one-half of the previous number.

4/2 = 2

2/2 = 1

1/2 = 1/2

(1/2)/2 = 1/4

(1/4)/2 = 1/8 and so on

Look at this series: 7, 10, 8, 11, 9, 12, ... What number should come next?

7

10

12

13

In the first pattern, 3 is added; in the second, 2 is subtracted and so on

Look at this series: 36, 34, 30, 28, 24, ... What number should come next?

20

22

23

26

This is an alternating number subtraction series. First, 2 is subtracted, then 4, then 2, and so on.

Look at this series: 53, 53, 40, 40, 27, 27, ... What number should come next?

12

14

27

53

each number is repeated, then 13 is subtracted to arrive at the next number.

Look at this series: 21, 9, 21, 11, 21, 13, 21, ... What number should come next?

14

15

21

23

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.

Look at this series: 58, 52, 46, 40, 34, ... What number should come next?

26

28

30

32

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

Look at this series: 3, 4, 7, 8, 11, 12, ... What number should come next?

7

10

14

15

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.

Look at this series: 31, 29, 24, 22, 17, ... What number should come next?

15

14

13

12

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

Look at this series: 544, 509, 474, 439, ... What number should come next?

404

414

420

445

Each number is 35 less than the previous number.

Look at this series: 2, 6, 18, 54, ... What number should come next?

108

148

162

216

This is a simple multiplication series. Each number is 3 times more than the previous number.

Look at this series: 8, 6, 9, 23, 87 , ... What number should come next?

128

226

324

429

8 x 1 - 2 = 6

6 x 2 - 3 = 9

9 x 3 - 4 = 23

23 x 4 - 5 = 87

87 x 5 - 6 = 429