Find the pair of numbers that can replace the question mark (?) in the series given below :
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Find the pair of numbers that can replace the question mark (?) in the series given below :
.
Solution
✅ Correct Option: 2
The trick is to read the second half of the cycle backwards and multiply consecutive pairs. Each cycle has 15 terms:
90, 180, 12, 50, 100, ?, ?, 3, 50, 4, 25, 2, 6, 30, 3
Take the tail in reverse order: 3, 30, 6, 2, 25, 4, 50, 3. Multiply each adjacent pair, and you generate the front of the series in order:
- 3 × 30 = 90 (1st term)
- 30 × 6 = 180 (2nd term)
- 6 × 2 = 12 (3rd term)
- 2 × 25 = 50 (4th term)
- 25 × 4 = 100 (5th term)
- 4 × 50 = 200 (6th term)
- 50 × 3 = 150 (7th term)
So the missing pair is 200 and 150, and the full cycle reads 90, 180, 12, 50, 100, 200, 150, 3, 50, 4, 25, 2, 6, 30, 3, which then repeats.