All most in all the entrance tests as well as interviews series based questions are asked to evaluate IQ. People who love mathematics definitely enjoy solving series related questions. This section is devoted to all such enthusiast brain buddies.

**1) 2, 12, 36, 80, 150, ?**

A. 250

B. 252

C. 200

D. 270

**ans.** B

**Explanation:**

A unique pattern has been made into use in this series.

All numbers are (n^3 + n^2) where n is 1, 2, 3 and so on.

**2) 6, 14, 26, 98, ?**

A. 276

B. 275

C. 220

D. 274

**ans.** A

**Explanation:**

6 = 1^1 + 2^1 + 3^1

14 = 1^2 + 2^2 + 3^2

36 = 1^3 + 2^3 + 3^3

98 = 1^4 + 2^4 + 3^4

Thus the next number will be

1^5 + 2^5 + 3^5 = 276

**3) 5, 16, 49, 104, ?**

A. 171

B. 191

C. 181

D. 161

**ans.** C

**Explanation:**

+11 =16

+33 =49

+55 =104

+77 =181

**4) 8, 7, 11, 12, 14, 17, 17, 22, ?**

A. 27

B. 20

C. 24

D. 22

**ans.** B

**Explanation:**

There are two series (8, 11, 14, 17, 20) and (7, 12, 17, 22) increasing by 3 and 5 respectively.

**5) 2, 6, 12, 20, 30, 42, 56, ?**

A. 61

B. 64

C. 70

D. 72

**ans.** D

**Explanation:**

The pattern is 1 x 2, 2 x 3, 3 x 4, 4 x 5, 5 x 6, 6 x 7, 7 x 8.

So, the next number is 8 x 9 = 72.

**6) 4, -8, 16, -32, 64, ?**

A. 128

B. -128

C. 192

D. -192

**ans.** B

**Explanation:**

Each number is the proceeding number multiplied by -2.

So, the required number is -128.

**7) 7, 26, 63, 124, 215, 342, ?**

A. 481

B. 511

C. 391

B. 421

**ans.** B

**Explanation:**

Numbers are (2^{3} – 1), (3^{3} – 1), (4^{3} – 1), (5^{3} – 1), (6^{3} – 1), (7^{3} – 1) etc.

So, the next number is (8^{3} – 1) = (512 – 1) = 511.

**8) 3, 12, 27, 48, 75, 108, ?**

A. 147

B. 183

C. 162

D. 192

**ans.** A

**Explanation:**

The numbers are 3 x 1^{2}, 3 X 2^{2}, 3 X 3^{2}, 3 X 4^{2}, 3 X 5^{2}, 3 X 6^{2}, Missing number= 3 X 7^{2} = 147

**9) 20, 19, 17, ?, 10, 5**

A. 14

B. 15

C. 13

D. 11

**ans.** A

**Explanation:**

The Pattern is – 1, – 2,…

Missing number = 17 – 3 = 14.

**10) 1, 6, 13, 22, 33, ?**

A. 44

B. 45

C. 46

D. 47

**ans. **C

**Explanation:**

The pattern is + 5, + 7, + 9, + 11,…

Missing number = 33 + 13 = 46.

**11) 24, 60, 120, 210, ?**

A. 300

B. 420

C. 336

D. 400

**ans.** C

**Explanation:**

The pattern is 36, 60, + 90, … i.e. + 16 x (6 + 0), + 16 x (6 + 4), + [6 * (6 + 9)], Missing number 210 + 16 x (6 + 15) = 210 + 126 = 336.

**12) 3, 6, 18, 72, ?**

A. 144

B. 360

C. 288

D. 216

**ans.** B

**Explanation:**

pattern is * 2, * 3,*4, number is = 72 x 5 = 360.

**13) 3, 7, 6, 5, 9, 3, 12, 1, 15, ?**

A. 18

B. 13

C. -1

D. 3

**ans.** C

**Explanation:**

There are two series, beginning respectively with 3 and 7. In one 3 is added and in another 2 is subtracted.

The next number is 1 – 2 = -1.

**14) 192, 021, 222, 324, 252, 627, 2_, 9_?**

A. 280, 930

B. 282, 930

C. 248, 920

D. 250, 940

**ans.** B

**Explanation:**

If you look closely, you will find a sequence in every alternating number.

192, 222 and 252 form one series where 30 is added each time.

021, 324 and 627 form one series where 303 is added each time.

Thus the next two numbers will be 282 and 930.

**15) 2, 4, 12, 48, 240,?**

A. 960

B. 1440

C. 1080

D. 1920

**ans.** B

**Explanation:**

Go on multiplying the given numbers by 2, 3, 4, 5, 6.

So, the correct next number is 1440.

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