What nonsense. I'd write 5+5+5, every time, because it is less handwriting than 3+3+3+3+3. To me, this shows that the kid was able to step back and optimize his

What nonsense. I'd write 5+5+5, every time, because it is less handwriting than 3+3+3+3+3. To me, this shows that the kid was able to step back and optimize his process, in addition to applying the rules of math. Those are definitely qualities you want in a programmer.