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 3 of 5.
Anand said:
1 decade ago
2nd, 4rd, 6th number are added +2 .
Hence answer is 15.
2nd number is 9 +2=11.
4th number is 11+2= 13.
6th number is 13+2=15.
Hence answer is 15.
2nd number is 9 +2=11.
4th number is 11+2= 13.
6th number is 13+2=15.
Shivam said:
9 years ago
You see that the series is,
21 - 9 = 12.
Again after 9 have 21.
Again you see 2,
And again 21 - 9.
You see that 10, 10, 8, 8, 6, 6 series has follows.
21 - 9 = 12.
Again after 9 have 21.
Again you see 2,
And again 21 - 9.
You see that 10, 10, 8, 8, 6, 6 series has follows.
Surya said:
1 decade ago
1st, 3rd, 5th, 7th place no's are same
2nd,4h,6th place are adding 2
9+2=11
11+2=13
13+2=15
ans=15
2nd,4h,6th place are adding 2
9+2=11
11+2=13
13+2=15
ans=15
Abi said:
1 decade ago
Hi, it cab be easily solved.
1st, 3rd, 5th, 7th place no's are same
2nd,4h,6th place are adding 2
9+2=11
11+2=13
13+2=15
ans=15
1st, 3rd, 5th, 7th place no's are same
2nd,4h,6th place are adding 2
9+2=11
11+2=13
13+2=15
ans=15
Jio said:
1 decade ago
It can be solved by the below method too
( 21, 9, 21, 11, 21, 13, 21_
21-12=9
9+12=21
21-10=11
11+10=21
21-8=13
13+8=21
21-6=15
This goes as -12+12,-10+10,-8+8,-6+6 where all digits get reduced by 2
( 21, 9, 21, 11, 21, 13, 21_
21-12=9
9+12=21
21-10=11
11+10=21
21-8=13
13+8=21
21-6=15
This goes as -12+12,-10+10,-8+8,-6+6 where all digits get reduced by 2
Akhilesh said:
1 decade ago
It is solved by another way i.e.
remove all alternate 21 and get differences between rest nos.
We'll get right answer i.e. B.
remove all alternate 21 and get differences between rest nos.
We'll get right answer i.e. B.
Vivek srivastava said:
1 decade ago
It is difference of number are 2
so
21-9=12
21-11=10
21-13=8
and
12-2=10
10-2=8
8-2=6
so
21-6=15
This is the right answer solved by vivek Srivastava.
so
21-9=12
21-11=10
21-13=8
and
12-2=10
10-2=8
8-2=6
so
21-6=15
This is the right answer solved by vivek Srivastava.
Saroj said:
1 decade ago
It is done in another way i.e..
by using decreasing order
11-9=2
13-11=2
15-13=2
so decrees the 2
by using decreasing order
11-9=2
13-11=2
15-13=2
so decrees the 2
Malkeet singh said:
1 decade ago
Another method:
21 is coming after every different number.
If we add 2 with every different number in ascending order automatic give the result.
For example:
different no. 9+2=11
different no. 11+2=13
different no. 13+2=15 and so on.
21 is coming after every different number.
If we add 2 with every different number in ascending order automatic give the result.
For example:
different no. 9+2=11
different no. 11+2=13
different no. 13+2=15 and so on.
M.RAGHURAM PGDM 1 said:
9 years ago
Take 21 alternatively and add 2 so, the answer is 15.
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