Sum of Digits.

[Dieter]

(03-26-2016 08:15 PM)ggauny@live.fr Wrote:  After seeying post #20 link in french, I am as before.
I think it is very simple solution but only for you.

The solution is simple because it is just x mod 9. ;-)
(Or 9 if this yields zero).

x=156: 1+5+6 = 12. Then 1+2 = 3
156 mod 9 = 3

x=12345: 1+2+3+4+5 = 15. Then 1+5 = 6
12345 mod 9 = 6

x=987654321: 9+8+7+6+5+4+3+2+1 = 45. Then 4+5 = 9
987654321 mod 9 = 0 => result is 9

Voilà – it's as simple as that.

(03-26-2016 08:15 PM)ggauny@live.fr Wrote:  15 : 1 5 I add and it is 6.

15 mod 9 = 6

(03-26-2016 08:15 PM)ggauny@live.fr Wrote:  In 3 steps ????

Well... OK, that's a real challenge. ;-)
But it can be done in four steps.

Franz used the more correct solution 1 + (x–1) mod 9 which can be coded in four steps as well. At least on the 34s.

Dieter