function sumOfMultiples(number) {
let sum = 0; for(let i=1; i<number; i++) {
if(i % 3 === 0 || i % 5 === 0){
sum += i;
}
}
return sum;
}
sumOfMultiples(10); // returns 23 as 3 + 5 + 6 + 9 = 23
sumOfMultiples(15); // returns 45 as 3 + 5 + 6 + 9 + 10 + 12 = 45