# PE 2 - Number Series | LR - Series

**PE 2 - Number Series | LR - Series**

0, 4, 6, 3, 7, 9, 6, ?, 12, 9, 13, 15

- A.
8

- B.
10

- C.
11

- D.
12

- E.
None of these

Answer: Option B

**Explanation** :

It is a combination of 3 series.

1^{st} series: 0, 3, 6, ...

2^{nd} series: 4, 7, 10, ...

3^{rd} series: 6, 9, 12, ...

In the 2^{nd} series, each term is increased by 3 to obtain the next term.

So, the missing term is 7 + 3 = 10

Hence, option (b).

Workspace:

**PE 2 - Number Series | LR - Series**

2, 6, 3, 15, 5, 20, 4, 28, ?

- A.
5

- B.
7

- C.
8

- D.
11

- E.
None of these

Answer: Option B

**Explanation** :

Terms on even places are product of their adjacent terms.

2 × 3 = 6

3 × 5 = 15

5 × 4 = 20

∴ 4 × ? = 28

⇒ ? = 7

Hence, option (b).

Workspace:

**PE 2 - Number Series | LR - Series**

7, 4, 5, 9, ?, 52.5, 160.5

- A.
18

- B.
19.5

- C.
20

- D.
20.5

Answer: Option C

**Explanation** :

2^{nd} term: 4 = 7 × 1/2 + 1/2

3^{rd} term: 5 = 4 × 1 + 1

4^{th} term: 9 = 5 × 3/2 + 3/2

∴ 5^{th} term: ? = 9 × 2 + 2 = 20

Hence, option (c).

Workspace:

**PE 2 - Number Series | LR - Series**

5, 348, 564, 689, ?, 780, 788

- A.
348

- B.
689

- C.
753

- D.
780

- E.
788

Answer: Option D

**Explanation** :

Let us calculate the difference between consecutive terms

348 – 5 = 343 = 7^{3}

564 – 348 = 216 = 6^{3}

689 – 564 = 125 = 5^{3}

753 – 689 = 64 = 4^{3}

Hence, the difference between consecutive terms is perfect cube and the next difference will be 3^{3} = 27

∴ Next term = 753 + 27 = 780.

Hence, option (d).

Workspace:

**PE 2 - Number Series | LR - Series**

4.5, 16, ?, 33, 38.5, 42, 43.5

- A.
16

- B.
25.5

- C.
33

- D.
38.5

- E.
42

Answer: Option B

**Explanation** :

Let us calculate the difference between consecutive terms.

16 – 4.5 = 11.5

? – 16 = ??

33 - ?? = ???

38.5 – 33 = 5.5

42 – 38.5 = 3.5

43.5 – 2 = 1.5

The difference between consecutive terms is itself decreasing by 2.

∴ ? – 16 = 9.5

⇒ ? = 25.5

Hence, option (b).

Workspace:

**PE 2 - Number Series | LR - Series**

14, 18, 82, 118, 630, ?

- A.
730

- B.
692

- C.
711

- D.
682

- E.
None of these

Answer: Option A

**Explanation** :

Let us calculate the difference between consecutive terms.

18 – 14 = = 2^{2}

82 – 18 = 64 = 4^{3}

118 – 82 = 36 = 6^{2}

630 – 118 = 512 = 8^{3}

Hence, the difference is alternately square and cube of consecutive even numbers.

∴ Next number should be 630 + 10^{2} = 730

Hence, option (a).

Workspace:

**PE 2 - Number Series | LR - Series**

11, 10, ?, 100, 1001, 1000, 10001

- A.
101

- B.
102

- C.
103

- D.
104

- E.
None of these

Answer: Option A

**Explanation** :

The pattern is:

-1, × 10 + 1, -1, × 10 + 1, -1, × 10 + 1

So, the missing term = 10 × 10 + 1 = 101

Hence, option (a).

Workspace:

**PE 2 - Number Series | LR - Series**

19, 97, 162, 214, 253, ?

- A.
277

- B.
279

- C.
224

- D.
280

- E.
None of these

Answer: Option B

**Explanation** :

Let us calculate the difference between consecutive terms.

97 – 19 = 78 = 6 × 13

162 – 97 = 65 = 5 × 13

214 – 162 = 52 = 4 × 13

253 – 214 = 39 = 3 × 13

∴ ? – 253 = 2 × 13 = 26

⇒ ? = 253 + 26 = 279

Hence, option (b).

Workspace:

**PE 2 - Number Series | LR - Series**

9, 15, 26, 42, 63, ?

- A.
79

- B.
87

- C.
89

- D.
77

- E.
None of these

Answer: Option C

**Explanation** :

Let us calculate the difference between consecutive terms.

15 – 9 = 6

26 – 15 = 11

42 – 26 = 16

63 – 42 = 21

∴ ? – 63 = 26

⇒ ? = 63 + 26 = 89

Hence, option (c).

Workspace:

**PE 2 - Number Series | LR - Series**

6, 10, 37, 53, 178, ?

- A.
210

- B.
212

- C.
214

- D.
216

- E.
None of these

Answer: Option C

**Explanation** :

Let us calculate the difference between consecutive terms.

10 – 6 = 4 = 2^{2}

37 – 10 = 27 = 3^{3}

53 – 37 = 16 = 4^{2}

178 – 53 = 125 = 5^{3}

∴ ? – 178 = 6^{2} = 36

⇒ ? = 178 + 36 = 214

Hence, option (c).

Workspace:

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