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.

Moni said:   1 decade ago
What is the answer for sum?

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

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

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

Sam said:   1 decade ago
10 teams participating in national football league. If each team plays the other team two times, the total number of games the league will play is.

Umang said:   1 decade ago
2-1 = 1*1
6-2 = 2*2
15-6 = 3*3
31-15 = 4*4
64-31 = 5*5

But 91-56 = 6*6 is not happening.

So 91 is odd no.

Rajesh said:   1 decade ago
@Kumar.

Your concept is OK. But same time you took the wrong concept.

First minus 1 by 2.

Then minus 6 by 2 how is it correct? OK now you understand.

But your thing is good.

Sikkanthar said:   1 decade ago
In this problem they are adding the result with square value of the natural numbers.
I mean.

1,
1(result) + (1*1) = 2.
2(result) + (2*2) = 6.
6(result) + (3*3) = 15.
15(result) + (4*4) = 31.
31(result) + (5*5) = 56.
56(result) + (6*6) = 92.

Now we are getting 92 not 91.. So 91 is the wrong number of the given.

Sonutalwani said:   1 decade ago
1 + (1*1) = 2.
2 + (2*2) = 6.
6 + (3*3) = 15.
15 + (4*4) = 31.
31 + (5*5) = 56.

56 + (6*6) = 92 (91 is wrong number).


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