CA Foundation · Quantitative Aptitude · Number Series, Coding-Decoding and Odd Man Out
In the series 5, 10, 20, 40, 80, ?, what is the missing number?
The missing number is 160. The series follows a pattern where each term is doubled to obtain the next term. Since 80 × 2 = 160, the answer is 160.
- A120
- B140
- C160Correct
- D180
Explanation
Each term is multiplied by 2 to get the next term. 5 × 2 = 10, 10 × 2 = 20, 20 × 2 = 40, 40 × 2 = 80, 80 × 2 = 160. Option 120 is wrong because it assumes adding 40 instead of doubling. Option 140 and 180 do not follow the doubling pattern.
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