# Number Series

Find the number that fits somewhere into the middle of the series. Some of the items involve both numbers and letters

Look at this series: U32, V29, __, X23, Y20, … What number should fill the blank?

**Answer**: (a)

**Explanation:**

In this series, the letters progress by 1; the numbers decrease by 3.

Look at this series: 0.15, 0.3, ____, 1.2, 2.4, … What number should fill the blank?

**Answer**: (c)

**Explanation:**

This is a simple multiplication series. Each number is 2 times greater than the previous number.

Look at this series: XXIV, XX, __, XII, VIII, … What number should fill the blank?

**Answer**: (c)

**Explanation:**

This is a simple subtraction series; each number is 4 less than the previous number.

Look at this series: 4, 7, 25, 10, __, 20, 16, 19, … What number should fill the blank?

**Answer**: (a)

**Explanation:**

Two series alternate here, with every third number following a different pattern. In the main series, 3 is added to each number to arrive at the next. In the alternating series, 5 is subtracted from each number to arrive at the next.

Look at this series: J14, L16, __, P20, R22, … What number should fill the blank?

**Answer**: (b)

**Explanation:**

In this series, the letters progress by 2, and the numbers increase by 2.

Look at this series: 72, 76, 73, 77, 74, __, 75, … What number should fill the blank?

**Answer**: (a)

**Explanation:**

This series alternates the addition of 4 with the subtraction of 3.

Look at this series: 15, __, 27, 27, 39, 39, … What number should fill the blank?

**Answer**: (d)

**Explanation:**

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.

Look at this series: 83, 73, 93, 63, __, 93, 43, … What number should fill the blank?

**Answer**: (c)

**Explanation:**

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.

Look at this series: (^{1}⁄_{9}), (^{1}⁄_{3}), 1, ____ , 9, … What number should fill the blank?

**Answer**: (b)

**Explanation:**

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

Look at this series: VI, 10, V, 11, __, 12, III, … What number should fill the blank?

**Answer**: (b)

**Explanation:**

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.

Look at this series: 8, 43, 11, 41, __, 39, 17, … What number should fill in the blank?

**Answer**: (b)

**Explanation:**

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.

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

**Answer**: (a)

**Explanation:**

In this series, 5 is added to the previous number; the number 70 is inserted as every third number.

Look at this series: V, VIII, XI, XIV, __, XX, … What number should fill the blank?

**Answer**: (d)

**Explanation:**

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

Look at this series: 664, 332, 340, 170, ____, 89, … What number should fill the blank?

**Answer**: (d)

**Explanation:**

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

Look at this series: F2, __, D8, C16, B32, … What number should fill the blank?

**Answer**: (c)

**Explanation:**

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

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