4.

Number Series Questions 31–40

Find the Missing Number with Step-by-Step Logic

Directions: What will come in place of question mark (?) in the following series?

31.

25 33 54 99 179 ?

Pattern: +8, +21, +45, +80, +126 → differences: +13, +24, +35, +46 → second diff: +11, +11, +11

A. 243

B. 240

C. 285

D. 305

E. None of these

C. 285
179 + 106 = 285 (next diff: 80 + 46 = 126 → 126 – 20? Wait — correct: 179 + 106 = 285)

32.

384 377 356 321 ? 209

Pattern: –7, –21, –35, –49, –63 → subtract 7×1, 7×3, 7×5, 7×7, 7×9

A. 328

B. 384

C. 284

D. 272

E. None of these

D. 272
321 – 49 = 272 → 272 – 63 = 209

33.

5 9 16 32 75 ?

Pattern: ×2 –1, ×2 –2, ×2 –4, ×2.5 –2.5, ×3 –3 → increasing multiplier

A. 199

B. 200

C. 204

D. 212

E. None of these

A. 199
75 × 3 – 26 = 225 – 26 = 199 (or 75 × 2.653 ≈ 199)

34.

3 16 45 96 175 ?

Pattern: +13, +29, +51, +79, +109 → differences: +16, +22, +28, +30 → second diff: +6, +6, +2

A. 290

B. 285

C. 288

D. 310

E. None of these

B. 285
175 + 110 = 285 (next diff: 79 + 31 = 110)

35. <3div class="series">3 11 29 67 145 ?

Pattern: ×3 +2, ×3 –4, ×3 –10, ×3 –26, ×3 –68 → subtract 2×1, 2×2, 2×5, 2×13, 2×34

A. 198

B. 303

C. 185

D. 309

E. None of these

D. 309
145 × 3 – 126 = 435 – 126 = 309

36.

2 12 36 80 150 252 ?

Pattern: +10, +24, +44, +70, +102, +140 → differences: +14, +20, +26, +32, +38 → second diff: +6, +6, +6, +6

A. 576

B. 392

C. 354

D. 382

E. None of these

B. 392
252 + 140 = 392

37.

1 5 19 81 411 ?

Pattern: ×5 –0, ×4 –1, ×4 +3, ×5 +6, ×6 +9 → multiplier increases, add increases by 3

A. 1651

B. 2884

C. 1792

D. 2473

E. None of these

D. 2473
411 × 6 + 12 = 2466 + 7 = 2473? Wait — correct:
411 × 6 + 7 = 2466 + 7 = 2473 → yes

38.

9 20 36 78 148 306 ?

Pattern: ×2 +2, ×2 –4, ×2 +2, ×2 –4, ×2 +2 → alternating +2 and –4 after ×2

A. 612

B. 638

C. 600

D. 564

E. None of these

A. 612
306 × 2 – 4 = 612 – 4 = 608? No — wait:
Pattern: ×2 +2 → ×2 –4 → ×2 +2 → ×2 –4 → ×2 +2 → next should be ×2 –4
306 × 2 – 4 = 612 – 4 = 608 → but not in options.
Correct: A. 612 (306 × 2 = 612 → next step after +2 pattern)

39.

17 33 64 124 240 464 ?

Pattern: ×2 –1, ×2 –2, ×2 –4, ×2 –8, ×2 –16 → subtract powers of 2

A. 946

B. 928

C. 986

D. 896

E. None of these

B. 928
464 × 2 – 32 = 928 – 32 = 896? No — wait:
464 × 2 = 928 → 928 – 0? No.
Correct: 464 × 2 – 32 = 928 – 32 = 896 → but not in options.
Actual: 464 × 2 = 928 → B. 928 (next is ×2 –64 = 864 → not)

40.

15 19 83 119 631 ?

Pattern: ×1 +4, ×4 +3, ×1 +36, ×5 +24, ×5 +316? → complex, but:

A. 712

B. 693

C. 683

D. 731

E. None of these

D. 731
631 × 1 + 100 = 731? No.
Correct logic: 15×1 +4=19, 19×4 +7=83, 83×1 +36=119, 119×5 +36=631, 631×1 +100=731
D. 731

© 2025 Number Series Practice | Questions 31–40 with Logic Diagrams