Aptitude - Odd Man Out and Series - Discussion
Discussion Forum : Odd Man Out and Series - Find Wrong No. (Q.No. 7)
Directions to Solve
Find out the wrong number in the series.
7.
1, 3, 10, 21, 64, 129, 356, 777
Answer: Option
Explanation:
A x 2 + 1, B x 3 + 1, C x 2 + 1, D x 3 + 1 and so on.
So, 356 is wrong.
Discussion:
11 comments Page 1 of 2.
Kuldeep choudhary said:
9 years ago
One more alternative method:-.
Separate out even & odd place numbers as 3, 21, 129, 777 & 1, 10, 64, 356.
Then find the difference between each other like 18, 108, 548 & 9, 54, 292.
Hereafter you will find the division of numbers are constant (i.e. Dividend=6), only 292 differs, then back this & 356 is the answer.
Separate out even & odd place numbers as 3, 21, 129, 777 & 1, 10, 64, 356.
Then find the difference between each other like 18, 108, 548 & 9, 54, 292.
Hereafter you will find the division of numbers are constant (i.e. Dividend=6), only 292 differs, then back this & 356 is the answer.
Sweety said:
1 decade ago
1, 3, 10, 21, 64, 129, 356, 777
3-1=2.
10-3=7.
21-10=11.
64-21=43.
129-64=65.
356-129=127.
777-356=421.
Answer should be 129. Because after subtracting in all the case give prime number except in 129-64 case.
3-1=2.
10-3=7.
21-10=11.
64-21=43.
129-64=65.
356-129=127.
777-356=421.
Answer should be 129. Because after subtracting in all the case give prime number except in 129-64 case.
(2)
Nagendramurthy said:
1 decade ago
Alternate method:
1=1
3=3
10=1+0=1
21=2+1=3
64=6+4=10=1+0=1
129=1+2+9=12=1+2=3
356=3+5+6=14=1+4=5( wrong one.. it should be 1)
777=7+7+7=21=2+1=3
Alternative 1 and 3 series.. this is method is correct..
1=1
3=3
10=1+0=1
21=2+1=3
64=6+4=10=1+0=1
129=1+2+9=12=1+2=3
356=3+5+6=14=1+4=5( wrong one.. it should be 1)
777=7+7+7=21=2+1=3
Alternative 1 and 3 series.. this is method is correct..
(2)
Riya said:
1 year ago
In the above solution, where we are separating as odd and even numbers, the difference between the last two odd numbers I.e., 777 and 129 is 648.
Also, 648/6 = 108 whereas 9 is not completely by 6.
Also, 648/6 = 108 whereas 9 is not completely by 6.
Imran said:
1 decade ago
a-1 and b=3 take first two number as a and b
1*2+1=3
3*3+1=10
10*2+1=21
21*3+1=64
64*2+1=129
129*3+1=388 but in the queston in 356 so 356 is worng
388*2+1=777
Is it clear 356 is wrong
1*2+1=3
3*3+1=10
10*2+1=21
21*3+1=64
64*2+1=129
129*3+1=388 but in the queston in 356 so 356 is worng
388*2+1=777
Is it clear 356 is wrong
(9)
Dhara said:
6 years ago
I think 64 should be the answer.
We are adding prime no 1 3 7 11 13 so 64 is wrong.
We are adding prime no 1 3 7 11 13 so 64 is wrong.
(1)
Aditya Kavlekar said:
7 years ago
As per my logic;.
Only 10 is multiple of 5 and rest are not. So odd one is 10.
Only 10 is multiple of 5 and rest are not. So odd one is 10.
Sarvani said:
9 years ago
64 is a perfect square number, rest all are not.
Anu said:
8 years ago
Thanks for the explanation.
Pradyumna said:
8 years ago
Thanks for the answers.
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