Number Series Questions With Answer Key

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Directions (Q. 1-10): find the missing number in the following number series?

1). 125,   152,   161,   169,   173,   ?,   175

  1. a)180
  2. b)174
  3. c)176
  4. d)184
  5. e)173

2). 27,   54,   162,   648,   ?,   19440

  1. a)3274
  2. b)3280
  3. c)3240
  4. d)3365
  5. e)3384

3). 161,   320,   636,   ?,   2512,   4992

  1. a)1329
  2. b)1340
  3. c)1264
  4. d)1380
  5. e)1348

4). 4032,   4290,     4556,   4830,   5112,   ?

  1. a)5329
  2. b)5402
  3. c)5302
  4. d)5529
  5. e)5482

5). 16,   ?,   296,   1192,   4776,   19112

  1. a)90
  2. b)80
  3. c)100
  4. d)75
  5. e)72

6). 584,   559,   608,   527,   ?,   479

  1. a)627
  2. b)648
  3. c)623
  4. d)608
  5. e)671

7). 36,   90,   ?,   1417.5,   7796.25,   50675.625

  1. a)275
  2. b)517
  3. c)364
  4. d)315
  5. e)385

8). 28,   29,   ?,   195,   796,   4005

  1. a)62
  2. b)68
  3. c)81
  4. d)83
  5. e)74

9). 15,   40,   70,   150,   ?,   590

  1. a)310
  2. b)280
  3. c)290
  4. d)300
  5. e)305

10). 205,   989,   364,   848,   487,   ?

  1. a)748
  2. b)745
  3. c)643
  4. d)648
  5. e)743

Solution With Answer Key:

1). B)

The series is +33 , +32, +23, +22, +13, +12, …..

125 + (3)3 = 152 ;   152 + (3)2 = 161 ;  161 + (2)3 = 169;   169 + (2)2 = 173

173 + (1)3 = 174;   174 + (1)2 = 175

2). C)

The series is x2, x3, x4, x5, x6,….

27 × 2 = 54;  54×3 = 162;  162 × 4 = 648;   648 × 5 = 3240

3240 × 6 = 19440

3). C)

The series is x2 — 21, x2 — 22, x2 – 23, x2 – 24, …

ie 161 x 2 — 2 = 320,

320 x 2 — 22 = 636,

636 x 2 — 23 = 1264,

1264 x 2 — 24 = 2512,

2512 x 2 — 25 = 4992,

4). B)

The series is 632 + 63 = 4032,

65+ 65 = 4290, 672 + 67 = 4556,

692 + 69 = 4830, 712 + 71 = 5112,

732 + 73 = 5402, …

5). E)

The series is

16 x 4 + 8 = 72

72 x 4 + 8 = 296

296 x 4 + 8 = 1192

1192 x 4 + 8 = 4776

4776 x 4 + 8 19112

6). B)

The series is —(5)2, +(7)2 – (9)2, +(11)2, —(13)2….

ie 584 — 52 = 559,

559 + 72 = 608,

608 – 92 = 527,

527 + 112 = 648,

648 — 132 = 479,

7). D)

The series is

36 x 2.5 = 90

90 x3.5 = 315

315 x4.5 = 1417.5

1417.5 x5.5 = 7796.25

7796.25 x6.5 = 5.675.625

8). A)

The series is x1 + 12, x2 + 22, x3 + 32, x4 + 42,

je 28 x 1 + 12= 29,

29 x 2 + 22 = 62,

62 x 3 + 32 = 195,

195 x 4 + 42 = 796,

796 x 5 + 52 = 4005,

9). C)

The series is x2 + 10, x2 — 10, x2 + 10, x2 – 10, …(repeated alternately)

ie 15 x 2 + 10 = 40,

40 x 2 — 10 = 70,

70 x 2 + 10 = 150,

150 x 2 — 10 = 290,

290 x 2 + 10 = 590,

10). E)

The series is 205 + (28)2 = 989,

989 – (25)2 = 364,

364 – (22)2 = 848.

848 — (19)2 = 487,

487 + (16)2 = 743,

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