Question

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

2, 7, 15, 29, 52, 87, ?

1. 137
2. 127
3. 117
4. 107
5. None of these

Answer 1

Correct Answer - Option 1 : 137

Considering the above series,

2, 7, 15, 29, 52, 87, ?

The logic of the series can be explained as,

7 – 2 = 5

15 – 7 = 8

29 – 15 = 14

52 – 29 = 23

87 – 52 = 35

Taking double difference,

8 – 5 = 3

14 – 8 = 6

23 – 14 = 9

35 – 23 = 12

By observing the pattern of double difference,

Next double difference will be 15.

So, Next difference will be 35 + 15 = 50

⇒ ? – 87 = 50

⇒ ? = 87 + 50

⇒ ? = 137

∴ The value of ? is 137