Question

What is the sum of all three digit number that are divisible by 17

Answer 1

Smallest 3-digit no which is divisible by 17= 102
Greatest 3- digit no. which is divisible by 17=986
here it forms an AP
a=102 an=986
d=17
an=a+(n-1)d
986=102+(n-1)17
n=53
So there are 53 terms which are divisible by 17
Now the sum of all the no.
Sn=n/2(a+l)d. l means the last term i.e. 986
S53=53/2(102+986)17
S53=9301
The sum of all the 3 digits no. which are divisible by 17 is 9301