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 1 of 2.
Anirudh Rohith said:
6 years ago
2, 6, 12, 20, 30, 42, 56, (....)
6-2 = 4
12-6 = 6
20-12 = 8
30-20 = 10
42-30 = 12
56-42 = 14
72-56 = 16
We can get the answer in this way also.
6-2 = 4
12-6 = 6
20-12 = 8
30-20 = 10
42-30 = 12
56-42 = 14
72-56 = 16
We can get the answer in this way also.
(3)
Karthik said:
7 years ago
1^2 + 1 = 2,
2^2 + 2 = 6,
3^2 + 3 =12,
4^2 + 4 = 20,
5^2 + 5 = 30,
6^2 + 6 = 42,
7^2 + 7 = 56,
8^2 + 8 = 72.
2^2 + 2 = 6,
3^2 + 3 =12,
4^2 + 4 = 20,
5^2 + 5 = 30,
6^2 + 6 = 42,
7^2 + 7 = 56,
8^2 + 8 = 72.
(1)
Sushant said:
6 years ago
The sequence is (1 * 1 + 1),
(2 * 2 + 2) ,
(3 * 3 + 3) ,
(4 * 4 + 4) ,
(5 * 5 + 5) ,
(6 * 6 + 6) ,
(7 * 7 + 7) ,
(8 * 8 + 8) ,
And Now, the answer is 72.
(2 * 2 + 2) ,
(3 * 3 + 3) ,
(4 * 4 + 4) ,
(5 * 5 + 5) ,
(6 * 6 + 6) ,
(7 * 7 + 7) ,
(8 * 8 + 8) ,
And Now, the answer is 72.
(1)
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
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
Ashi said:
1 decade ago
Another way :
2/1*3 = 6.
6/2*4 = 12.
12/3*5 = 20.
20/4*6 = 30.
30/5*7 = 42.
42/6*8 = 56.
56/7*9 = 72.
So answer is 72.
2/1*3 = 6.
6/2*4 = 12.
12/3*5 = 20.
20/4*6 = 30.
30/5*7 = 42.
42/6*8 = 56.
56/7*9 = 72.
So answer is 72.
Hari said:
1 decade ago
6-2 = 4.
12-6 = 6.
20-12 = 8.
30-20 = 10.
42-30 = 12.
56-42 = 14.
x-56 = 16.
x = 72.
Answer = 72.
12-6 = 6.
20-12 = 8.
30-20 = 10.
42-30 = 12.
56-42 = 14.
x-56 = 16.
x = 72.
Answer = 72.
Kartik said:
9 years ago
The another logic is 1^2 + 1, 2^2 + 2, 3^2 + 3, 4^2 + 4.
Jay said:
9 years ago
Follow this method.
2^2 - 2.
3^2 - 3.
4^2 - 4.
5^2 - 5, and so on...
2^2 - 2.
3^2 - 3.
4^2 - 4.
5^2 - 5, and so on...
Hema said:
9 years ago
The sequence is (1 * 1 + 1),
(2 * 2 + 2),
(3 * 3 + 3),
(4 * 4 + 4),
(5 * 5 + 5),
(6 * 6 + 6),
(7 * 7 + 7),
(8 * 8 + 8),
Now, the answer is 72.
(2 * 2 + 2),
(3 * 3 + 3),
(4 * 4 + 4),
(5 * 5 + 5),
(6 * 6 + 6),
(7 * 7 + 7),
(8 * 8 + 8),
Now, the answer is 72.
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