October 21, 2016 by LanceShi

# 6.2 Calculate multiples of 3 and 5

## The problem

This is the first question in Euler Project:

*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*

Euler Project is a very good place to practice your programming. I would encourage you to try more questions in the archive. Most question might be too hard for you at this point. Don’t be discouraged.

## The code

Integer sum = 0; for(Integer i = 3; i < 1000; i++) { if(Math.mod(i, 3) == 0 || Math.mod(i, 5) == 0) { sum += i; } } System.debug('Sum is: ' + sum);

The result should be 233168.

As you can see, the code is not much more complicated than the last one. By understanding the concepts we have already learnt, we can actually resolve a lot of programming issues now!

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