Answer is 81 as you will add the multiples of 5 after each no.
6+5=11
11+10=21
21+15=36
36+20=56
56+25=81
Ans 3:
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Priyanshu
from
S. D. Memorial Sr. Sec. School, Gurgaon
Class : Class 9
Answer will be 81 because the series continues with a progression of table of 5
6+5=11
11+10=21
21+15=36
36+20=56
Then the next number which will be added is 25
then our series will be
56+25=81
Ans 4:
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Rudra kumar
from
Jawahar Navodaya vidyalaya, Sherghati
Class : Class 9
6+5=11 ,11+10=21,21+15=36,36+20=56 next add 25 as by series than 56+25=81