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:
46 comments Page 3 of 5.
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.
Abhay ide said:
10 years ago
By adding the given numbers.
21 + 9 = 30.
21 + 11 = 32.
21 + 13 = 34.
21 + 15 = 36.
This increased by 2 numbers.
21 + 9 = 30.
21 + 11 = 32.
21 + 13 = 34.
21 + 15 = 36.
This increased by 2 numbers.
Sheenam said:
10 years ago
Yes, 11 + 2 = 13.
13 + 2 = 15.
This is very easy question but my according this question is very confused.
13 + 2 = 15.
This is very easy question but my according this question is very confused.
Alisha said:
10 years ago
21+0 = 21, 9+2 = 11, 21+0 = 21, 11+2 = 13, 21+0 = 21, 13+2 = 15.
Answer: 15.
Answer: 15.
BHUMIT DOBARIYA said:
1 decade ago
ODD POSITION : 21 21 21 21.
EVEN POSITION : 9 11 13 15 (ADD 2).
EVEN POSITION : 9 11 13 15 (ADD 2).
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
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.
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.
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
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
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