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:
10 comments Page 1 of 1.
Dhara said:
5 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.
Aditya Kavlekar said:
5 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.
Pradyumna said:
6 years ago
Thanks for the answers.
Anu said:
6 years ago
Thanks for the explanation.
Ankush said:
7 years ago
Agree @Imran.
Kuldeep choudhary said:
7 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.
Sarvani said:
7 years ago
64 is a perfect square number, rest all are not.
Sweety said:
10 years 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.
(1)
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
(3)
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..
(1)
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