# Number Series

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

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

**Answer**: (b)

**Explanation:**

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 ...

Look at this series: 5.2, 4.8, 4.4, 4, … What number should come next?

**Answer**: (d)

**Explanation:**

In this simple subtraction series, each number decreases by 0.4.

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

**Answer**: (c)

**Explanation:**

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

Look at this series: 80, 10, 70, 15, 60, … What number should come next?

**Answer**: (a)

**Explanation:**

This is an alternating addition and subtraction series. In the first pattern, 10 is subtracted from each number to arrive at the next. In the second, 5 is added to each number to arrive at the next.

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

**Answer**: (a)

**Explanation:**

This is a simple subtraction series. Each number is 35 less than the previous number.

Look at this series: 201, 202, 204, 207, … What number should come next?

**Answer**: (d)

**Explanation:**

In this addition series, 1 is added to the first number; 2 is added to the second number; 3 is added to the third number; 4 is added to the fourth number; and go on.

Look at this series: 2, 4, 6, 8, 10, … What number should come next?

**Answer**: (b)

**Explanation:**

This is a simple addition series. Each number increases by 2.

Look at this series: 14, 28, 20, 40, 32, 64, … What number should come next?

**Answer**: (b)

**Explanation:**

This is an alternating multiplication and subtracting series: First, multiply by 2 and then subtract 8.

Look at this series: 1.5, 2.3, 3.1, 3.9, … What number should come next?

**Answer**: (c)

**Explanation:**

In this simple addition series, each number increases by 0.8.

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

**Answer**: (a)

**Explanation:**

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

Look at this series: 8, 22, 8, 28, 8, … What number should come next?

**Answer**: (c)

**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.

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

**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.

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

**Answer**: (a)

**Explanation:**

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

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

**Answer**: (d)

**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.

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

**Answer**: (c)

**Explanation:**

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

Look at this series: 22, 21, 23, 22, 24, 23, … What number should come next?

**Answer**: (c)

**Explanation:**

In this simple alternating subtraction and addition series; 1 is subtracted, then 2 is added, and so on.

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

**Answer**: (b)

**Explanation:**

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

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

**Answer**: (b)

**Explanation:**

This is a simple alternating addition and subtraction series. In the first pattern, 3 is added; in the second, 2 is subtracted.

Look at this series: 2, 1, (^{1}⁄_{2}), (^{1}⁄_{4}), … What number should come next?

**Answer**: (b)

**Explanation:**

This is a simple division series; each number is one-half of the previous number.

In other terms to say, the number is divided by 2 successively to get the next result.

^{4}⁄_{2} = 2

^{2}⁄_{2} = 1

^{1}⁄_{2} = ^{1}⁄_{2}

^{(1⁄2)}/_{2} = ^{1}⁄_{4}

^{(1⁄4)}/_{2} = ^{1}⁄_{8} and so on.

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