Logical Reasoning - Number Series - Discussion
Discussion Forum : Number Series - Type 1 (Q.No. 6)
Directions to Solve
In each series, look for the degree and direction of change between the numbers. In other words, do the numbers increase or decrease, and by how much
6.
Look at this series: 21, 9, 21, 11, 21, 13, 21, ... What number should come next?
Answer: Option
Explanation:
In this alternating repetition series, the random number 21 is interpolated every other number into an otherwise simple addition series that increases by 2, beginning with the number 9.
Discussion:
45 comments Page 4 of 5.
Jhansi said:
9 years ago
Logic : 21 becomes constant and alternate number should add 2.
Swarnendu said:
9 years ago
21 remains interpolated and 2 is added to the number.
Rajini arunkumar said:
8 years ago
21-12 = 9
9+12 = 21
21-10 = 11
11+10 = 21
21-8 = 13
13+8 = 21
21-6 = 15.
Why substracting 6 means, they subtracting adding like 10,8 so next even no.is 6 only.
9+12 = 21
21-10 = 11
11+10 = 21
21-8 = 13
13+8 = 21
21-6 = 15.
Why substracting 6 means, they subtracting adding like 10,8 so next even no.is 6 only.
(1)
Muzaan ul aazeem said:
8 years ago
Adding and subtracting both we can use in descending or ascending.
Eerappa said:
7 years ago
The second digit is 9,
4th digit is 11.
so alternatively adding two numbers,
after 3 the next is 15.
9,11,13,15..
4th digit is 11.
so alternatively adding two numbers,
after 3 the next is 15.
9,11,13,15..
(4)
Bhagyalakshmi dayal said:
7 years ago
@Akhilesh.
Thanks this is the simplest one. Thanks for the explanation.
Thanks this is the simplest one. Thanks for the explanation.
(3)
Sreenivas said:
6 years ago
@All. According to me,
21 - 12 = 9.
9 + 12 = 21.
21 - 10 = 11.
11 + 10 = 21.
21 - 8 = 13.
13 + 8 = 21.
21 - 6 = 15.
15 + 6 = 21.
21 - 12 = 9.
9 + 12 = 21.
21 - 10 = 11.
11 + 10 = 21.
21 - 8 = 13.
13 + 8 = 21.
21 - 6 = 15.
15 + 6 = 21.
(13)
Aadesh Rastogi said:
6 years ago
2 * 4 = 8
8 + 1 = 9
2 * 5 = 10
10 + 1 = 11
2 * 6 = 12
12 + 1 = 13
2 * 7 = 14
14 + 1 = 15 and so on.
8 + 1 = 9
2 * 5 = 10
10 + 1 = 11
2 * 6 = 12
12 + 1 = 13
2 * 7 = 14
14 + 1 = 15 and so on.
(9)
Rupesh Kumar Yadav said:
3 years ago
11-9 = 2.
13-11 = 2.
So, 15-13 = 2.
And next
different will be 2.
9,11,13 Next number will be 15.
13-11 = 2.
So, 15-13 = 2.
And next
different will be 2.
9,11,13 Next number will be 15.
(11)
Oliyad olana said:
3 years ago
Good, thanks everyone for explaining.
(11)
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