Sum of numbers of a number

Question

Say I have the number 123

Is there a computationally efficient way of adding 1+2+3 and getting the answer back

Ideally I'd avoid division or parsing to String as I feel this can be quite inefficient.

So you want to add all the digits together? – Tunaki Apr 09 '16 at 12:49 — Tunaki, Apr 09 '16 at 12:49
You can't ask *this* on Code Review. There's no code. – nhgrif Apr 09 '16 at 13:15 — nhgrif, Apr 09 '16 at 13:15

score 1 · Accepted Answer · answered Apr 09 '16 at 12:50

1

No need of parsing to string.

int sum=0;
while(n>0)
{
    sum += n%10; // add the last digit
    n/=10;  // remove the last digit.
}

answered Apr 09 '16 at 12:50

dryairship

Oh yes, but he want to avoid division. – Đăng Khoa Huỳnh Apr 09 '16 at 13:03
No, @ĐăngKhoaHuỳnh, he want's something as efficient as possible and he is potentially mistaken in thinking that division is not the most efficient way. – nhgrif Apr 09 '16 at 13:16
@Gabrielus You may use recursive methods. – dryairship Apr 11 '16 at 11:41

1 Answers1