The sum of all two digit numbers divisible by 5 is
The sum of all two digit numbers divisible by 5 is
Answer/Solution
945
Steps/Work
Required numbers are 10,15,20 . . . . . 95
This is an A.P. in which a=10,d=5 and l=95.
Let the number of terms in it be n.Then t=95
So a+(n-1)d=95.
10+(n-1)*5=95,
10+5n-5=95
5+5n=95
5n=95-5
n = 90/5
then n=18.
Required sum
=n/2(a+l)
=18/2(10+95)
=945
Answer is A.
This is an A.P. in which a=10,d=5 and l=95.
Let the number of terms in it be n.Then t=95
So a+(n-1)d=95.
10+(n-1)*5=95,
10+5n-5=95
5+5n=95
5n=95-5
n = 90/5
then n=18.
Required sum
=n/2(a+l)
=18/2(10+95)
=945
Answer is A.