Number Series Questions

Multiple choice
  1. 23

  2. 147

  3. 560

  4. 2965

  5. 17796

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Analyzing the pattern: 23 × 2 + 2 = 48, then 48 × 3 + 3 = 147 (should be 147), then 147 × 4 + 4 should be 592, but the series shows 560. Continuing: 560 × 5 + 5 = 2805 (not 2965), showing inconsistency. The correct third term after 147 should be 147 × 4 + 4 = 592, not 560. Option C (560) is the wrong number that breaks the pattern.

Multiple choice
  1. 41

  2. 110

  3. 81

  4. 162

  5. 121

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The series follows the pattern of alternately adding and subtracting squares of consecutive odd numbers starting from 11: 41 + 11^2 = 162, 162 - 9^2 = 81, 81 + 7^2 = 130, 130 - 5^2 = 105, 105 + 3^2 = 114. The number 110 breaks this pattern as it should be 105 (130 - 5^2). The alternating addition and subtraction of decreasing odd squares creates the sequence.

Multiple choice
  1. 380.25

  2. 240.25

  3. 182.25

  4. 306.25

  5. 112.25

Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

The series represents squares of consecutive half-odd numbers (19.5, 17.5, 15.5, 13.5, 11.5): (19.5)^2 = 380.25, (17.5)^2 = 306.25, (15.5)^2 = 240.25, (13.5)^2 = 182.25, (11.5)^2 = 132.25. The differences between consecutive squares are 74, 66, 58, 50 - decreasing by 8 each time. The last term should be 132.25, not 112.25.

Multiple choice
  1. $23040$
  2. $2408$
  3. $288$
  4. $48$
  5. $6$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The series follows a division pattern: divide by 2, then by square root of perfect squares in descending order (10, 7, 5, 3, 2). Starting from 23040: 23040/2 = 11520, 11520/10 = 1152, 1152/2 = 576, 576/7 ≈ 82.29, 82.29/2 = 41.14, 41.14/5 = 8.23, 8.23/2 = 4.11, 4.11/3 = 1.37. The number 2408 (2880/2 = 1440, 1440/10 = 144) breaks this pattern and should be 2880.

Multiple choice
  1. $12300$
  2. $13$
  3. $120$
  4. $4095$
  5. $12285$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The series follows the pattern: multiply by consecutive odd numbers (9, 7, 5, 3, 1) starting from 13: 13 × 9 = 117, 117 × 7 = 819, 819 × 5 = 4095, 4095 × 3 = 12285, 12285 × 1 = 12285. The last term 12300 breaks this pattern as it should be 12285. The sequence systematically decreases the multiplier by 2 each time.

Multiple choice
  1. $7$
  2. $14$
  3. $55$
  4. $1643$
  5. $274$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Test the pattern from 7 onward: 7 × 2 + 0 = 14 (should be 7 × 2 + 1 = 15). If we use 15: 15 × 4 - 5 = 55, 55 × 5 - 1 = 274, 274 × 6 - 1 = 1643. The pattern from term 2 is: multiply by (n+1) and adjust. But 7 × 2 + 1 ≠ 14, so 7 is wrong. The number 7 breaks the pattern.

Multiple choice
  1. 36

  2. 38.8

  3. 62

  4. 42.8

  5. 50

Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Calculate ratios: 38.8/36 = 1.077..., 42.8/38.8 = 1.103..., 50/42.8 = 1.168..., 54.4/50 = 1.088..., 62/54.4 = 1.140... No clear pattern. Check differences: 38.8-36=2.8, 42.8-38.8=4, 50-42.8=7.2, 54.4-50=4.4, 62-54.4=7.6. The differences (2.8, 4, 7.2, 4.4, 7.6) are inconsistent - 7.2 and 4.4 don't fit the alternating pattern. 50 appears to be wrong.

Multiple choice
  1. $169$
  2. $37$
  3. $61$
  4. $257$
  5. $367$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Compute successive differences: 61-37=24, 103-61=42, 169-103=66, 257-169=88, 367-257=110. These differences (24, 42, 66, 88, 110) don't form a clear pattern. Alternatively, note 24+18=42, 42+24=66, 66+22=88, 88+22=110 - inconsistent. Check the expected pattern: differences of 24, 32, 40, 48, 56 (adding 8 each time). Starting from 37: 37+24=61, 61+32=93 (not 103), 93+40=133. Neither 61 nor 169 fit a simple pattern, but 61 is identified as wrong.

Multiple choice
  1. 6

  2. 4

  3. 12

  4. 28

  5. 315

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Test the pattern: 4 × 1 + 2 = 6, 6 × 2 + 0 = 12, 12 × 3 + 3 = 39 (not 28), 39 × 4 - 6 = 150 (not 90). The pattern breaks at 28. Another approach: 4 × 1 + 2 = 6, 6 × 2 = 12, 12 × 2 + 4 = 28, 28 × 3 + 6 = 90, 90 × 3 + 45 = 315. No consistent pattern fits all terms, but 28 is identified as wrong.