How to find the sum of three digit numbers divisible by 7

by Suseela
(New York)

To find the first three digit number divisible by 7, divide 100, 101, 102.... by 7. When you do so, you will get 105 is the first three digit number divisible by 7. To get the scuccessive three digit numbers divisible by7, add 7 to the previous number. Then, we get 105, 112, 119,.... so on. To get the last three digit number divisible by7, divide 999, 998, 997 by 7, untill you get a last three digit number divisible by 7.

105, 112, 119,.....

The above sequence form an arithmetic progression, Use the sum of the terms of nan arithmetic series formula to find the sum of the above terms. Then you will get the sum of three digit numbers divisible by 7.

Hope this helps!