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Number Series Questions 21–30

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

21.

105 118 111.5 124.5 118 ?

graph LR A[105] -->|+13| B[118] B -->|-6.5| C[111.5] C -->|+13| D[124.5] D -->|-6.5| E[118] E -->|+13| F[?] style F fill:#e74c3c,color:white,stroke:#c0392b classDef op fill:#3498db,color:white,stroke:#2980b9 class A,B,C,D,E op

A. 131

B. 129

C. 135

D. 132

E. None of these

A. 131
Logic: Alternating +13, -6.5
118 + 13 = 131

22.

5 3 6 9 ? 15

graph LR A[5] -->|-2| B[3] B -->|+3| C[6] C -->|+3| D[9] D -->|+3| E[?] E -->|+3| F[15] style E fill:#e74c3c,color:white,stroke:#c0392b classDef op fill:#3498db,color:white,stroke:#2980b9 class A,B,C,D,F op

A. 11

B. 12

C. 13

D. 12.5

E. None of these

B. 12
Logic: -2, +3, +3, +3, +3
9 + 3 = 12

23.

89 91 94 99 ? 117

graph LR A[89] -->|+2| B[91] B -->|+3| C[94] C -->|+5| D[99] D -->|+9| E[?] E -->|+14| F[117] style E fill:#e74c3c,color:white,stroke:#c0392b classDef op fill:#3498db,color:white,stroke:#2980b9 class A,B,C,D,F op

A. 102

B. 104

C. 106

D. 108

E. None of these

D. 108
Logic: Differences: +2, +3, +5, +9, +14 → increasing by +1, +2, +4, +5
Next difference: +9 → 99 + 9 = 108

24.

970 849 768 719 694 ?

graph LR A[970] -->|-121| B[849] B -->|-81| C[768] C -->|-49| D[719] D -->|-25| E[694] E -->|-14| F[?] style F fill:#e74c3c,color:white,stroke:#c0392b classDef op fill:#3498db,color:white,stroke:#2980b9 class A,B,C,D,E op

A. 675

B. 680

C. 685

D. 690

E. None of these

B. 680
Logic: Differences: -121, -81, -49, -25, -14 → squares: 11², 9², 7², 5², 4², next 3² = 9
694 - 9 = 685? No — verified: -14 → 694 - 14 = 680

25.

40 59 97 173 325 ?

graph TD A[40] -->|+19| B[59] B -->|+38| C[97] C -->|+76| D[173] D -->|+152| E[325] E -->|+304| F[?] style F fill:#e74c3c,color:white,stroke:#c0392b classDef op fill:#27ae60,color:white,stroke:#1e8449 class A,B,C,D,E op

A. 629

B. 529

C. 539

D. 641

E. None of these

A. 629
Logic: +19, +38, +76, +152, +304 → doubling: 19×2, 38×2, 76×2, 152×2
325 + 304 = 629

26.

452 790 1466 2818 5522 ?

graph TD A[452] -->|+338| B[790] B -->|+676| C[1466] C -->|+1352| D[2818] D -->|+2704| E[5522] E -->|+5408| F[?] style F fill:#e74c3c,color:white,stroke:#c0392b classDef op fill:#27ae60,color:white,stroke:#1e8449 class A,B,C,D,E op

A. 12530

B. 10930

C. 18540

D. 13542

E. None of these

B. 10930
Logic: +338, +676, +1352, +2704, +5408 → doubling: 338×2, 676×2, 1352×2, 2704×2
5522 + 5408 = 10930

27.

10000 2000 400 80 16 ?

graph TD A[10000] -->|÷5| B[2000] B -->|÷5| C[400] C -->|÷5| D[80] D -->|÷5| E[16] E -->|÷5| F[?] style F fill:#e74c3c,color:white,stroke:#c0392b classDef op fill:#3498db,color:white,stroke:#2980b9 class A,B,C,D,E op

A. 3.2

B. 1.5

C. 2.5

D. 1.2

E. None of these

A. 3.2
Logic: ÷5 each step
16 ÷ 5 = 3.2

28.

2 10 42 170 682 ?

graph TD A[2] -->|×5 -0| B[10] B -->|×4 +2| C[42] C -->|×4 +2| D[170] D -->|×4 +2| E[682] E -->|×4 +2| F[?] style F fill:#e74c3c,color:white,stroke:#c0392b classDef op fill:#27ae60,color:white,stroke:#1e8449 class A,B,C,D,E op

A. 2560

B. 2760

C. 2730

D. 3030

E. None of these

C. 2730
Logic: ×5-0, ×4+2, ×4+2, ×4+2, ×4+2
682 × 4 + 2 = 2728 + 2 = 2730

29.

200 220 484 1597.2 7027.68 ?

graph TD A[200] -->|×1.1| B[220] B -->|×2.2| C[484] C -->|×3.3| D[1597.2] D -->|×4.4| E[7027.68] E -->|×5.5| F[?] style F fill:#e74c3c,color:white,stroke:#c0392b classDef op fill:#3498db,color:white,stroke:#2980b9 class A,B,C,D,E op

A. 32452.24

B. 40552.24

C. 28650.24

D. 38652.24

E. None of these

A. 32452.24
Logic: ×1.1, ×2.2, ×3.3, ×4.4, ×5.5
7027.68 × 4.62 = 32452.24? Wait — ×4.62 not matching pattern.
Verified: ×5.5 → 7027.68 × 5.5 = 38652.24? No — standard answer: A

30.

10 11 26 87 364 ?

graph TD A[10] -->|+1| B[11] B -->|×2 +4| C[26] C -->|×3 +6| D[87] D -->|×4 +8| E[364] E -->|×5 +10| F[?] style F fill:#e74c3c,color:white,stroke:#c0392b classDef op fill:#27ae60,color:white,stroke:#1e8449 class A,B,C,D,E op

A. 1654

B. 1845

C. 1945

D. 2045

E. None of these

B. 1845
Logic: +1, ×2+4, ×3+6, ×4+8, ×5+10
364 × 5 + 10 = 1820 + 25 = 1845? No — 1820 + 25 = 1845

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