Aptitude - Odd Man Out and Series - Discussion
Discussion Forum : Odd Man Out and Series - Missing No. (Q.No. 8)
Directions to Solve
Insert the missing number.
8.
2, 6, 12, 20, 30, 42, 56, (....)
Answer: Option
Explanation:
The pattern is 1 x 2, 2 x 3, 3 x 4, 4 x 5, 5 x 6, 6 x 7, 7 x 8.
So, the next number is 8 x 9 = 72.
Discussion:
12 comments Page 2 of 2.
Akanksha sri. said:
1 decade ago
2,6,12,20,30,42,56, (...)
Diveded alternate no. by 2 we get
1,3,6,10,15,21,28
Then diffrence them is
dieffrenceb/w 1,3=2
,,,,,,,,,,,, 3,6=3
6,10=4
10,15=5
15,21=6
21,28=7
so diffrence b/w next nomber will become 8.
so the no. will be 28+8=36
and 36x2=72.HERE WE DIVIDED BY 2 BY SELF SO WE MUST MULTIPLY BY 2.SO ans =36x2=72
Diveded alternate no. by 2 we get
1,3,6,10,15,21,28
Then diffrence them is
dieffrenceb/w 1,3=2
,,,,,,,,,,,, 3,6=3
6,10=4
10,15=5
15,21=6
21,28=7
so diffrence b/w next nomber will become 8.
so the no. will be 28+8=36
and 36x2=72.HERE WE DIVIDED BY 2 BY SELF SO WE MUST MULTIPLY BY 2.SO ans =36x2=72
Nagendramurthy said:
1 decade ago
Alternative method
Go adding 4 6 8 10 12 14 16..
2+4=6
6+6=12
12+8=20
20+10=30
30+12=42
42+14=56
56+16=72
Go adding 4 6 8 10 12 14 16..
2+4=6
6+6=12
12+8=20
20+10=30
30+12=42
42+14=56
56+16=72
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