Problem 1

Multiples of 3 and 5

If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23.

Find the sum of all the multiples of 3 or 5 below 1000.

var num = 1000;
var sum = 0;

for( var i = 0; i < num; i++) {
    if( i % 3 === 0 || i % 5 === 0) {
        sum+=i;
    }
}
console.log(sum);