Aptitude - Odd Man Out and Series - Discussion

Discussion Forum : Odd Man Out and Series - Pick Wrong No. (Q.No. 5)
Directions to Solve
Find out the wrong number in the given sequence of numbers.

5.
1, 2, 6, 15, 31, 56, 91
31
91
56
15
Answer: Option
Explanation:

1, 1 + 12 = 2, 2 + 22 = 6, 6 + 32 = 15, 15 + 42 = 31, 31 + 52 = 56, 56 + 62 = 92

Last number of given series must be 92 not 91.

Discussion:
22 comments Page 2 of 3.

Debasish said:   1 decade ago
6-2 = 4 = 2*2.
15-6 = 9 = 3*3.
31-15 = 16 = 4*4.
56-31 = 25 = 5*5.
91-56 = 35! = 6*6.

Manish said:   9 years ago
If we see prime numbers. Then 31 will be the answer. So which is the correct answer?

Fathima said:   9 years ago
31 is the only prime number.

Why not the answer is 31? Some one explain.

Beda said:   1 decade ago
In question 31 is the only prime number. So why the answer is not 31?

Rajeswari Yarra said:   2 years ago
Easy to Understand. Thanks everyone for explaining the answer.
(1)

Aditya said:   9 years ago
2, 5, 15, 131, 530, 13257 find out wrong number of the series.

Saran said:   1 decade ago
Answer is 91 but calculate answer is 92. So it is a wrong no.

Harsh said:   1 decade ago
Only the sum of first and last number is divisible by 5.

Sreeram said:   10 years ago
Why not 31? It's the only prime number.

Dhivya said:   1 decade ago
Can someone explain this clearly ?


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