Question

Find the sum of all the multiples of 3 in between 100 and 1000.

Please show work/explain.
Due 1:00pm Tomorrow

Answer 1

The awnser is 165,150

Answer 2

Explanation:

We have to find the sum of 102 + 105 + 108 + ... + 996 + 999.

Notice that 102 = 3 * 34 and 999 = 3 * 333. Hence there are 333 - 34 + 1 = 300 terms.

Hence the sum is 300(102 + 999)/2 = 1101 * 150 = 165,150.