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.

**Running time:** Unknown

**Assessment:** First code I’d written in 7-8 years. I hadn’t started measuring execution time yet, so I’m not sure how long it took to run, but it’s basically instantaneous.

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#include <iostream> using namespace std; int main() { int total = 0; for (int i = 0; i < 1000; i++) { if( (i % 3 == 0) || (i % 5 == 0) ) total += i; } cout << total; return 0; } |

Wrong answer…………

Incorrect.