(11C) Digit Sum

[Dieter]

Gamo, this is one of your best-coded programs. And it uses a clever algorithm: it sums 1/10 of the digits and finally multiplies the result by 10. Which is obtained by two consecutive 10^x commands (0 → 1 → 10).

I like such little tricks (altough a plain 10 is faster and doesn't require more steps). Let me add one more: If you want to zero data register 1 without affecting the stack, a simple STO 1 STO–1 does it. Saves one step here.

By the way...

(01-16-2018 08:52 AM)Gamo Wrote:  In mathematics, the digit sum of a given integer is the sum of all its digits
The digit sum of 84001 is calculated as 8+4+0+0+1 = 13

And the digit sum of this (the digital root) is 4 (simply run the program once more).
But you can calculate this directly, it's simply n mod 9. Or 9 if this yields zero (and n≠0).

Dieter