SPM Practice 1 (Arithmetic Progression) : Question 7

Example 7

Find the sum of all the multiples of 7 between 100 and 500.

[Multiple of 7 is 7, 14, 21, 28,......]
[Hint : You have to form the progression, solve for n and then find the sum using the Sn formula
Click here : You can find the number of terms in an AP if you know the last term]