Sum of Digits

Here's one method, although it's a little kludgy.

Say your number is in cell B2.

In a series of adjacent cells to the right enter these formulas:

=mid(B2,1,1)
=mid(B2,2,1)
=mid(B2,3,1)
. . .
=mid(B2.x,1) where 'x' is the maximum number of digits for which you're likely to want to find a digit sum.

Assume you've entered these formulas in cells C2 through G2. In cell H2 enter the formula =C2 D2+E2+F2G2. (Sum(C2:G2) results in a '0' for some reason.)

You can hide the interim columns, C through G, to make the table look cleaner.

I have tried combining the MID formulas into a single cell (=mid(B2,1,1) mid(B2,2,1)mid(B2,3,1) ) but it results in an error if the number of digits is less than the number of 'Mid' statements (or to put it another way, if the number of 'Mid' statements is greater than the number or digits.)

There may be a more elegant solution out there, but I'm too tired to look for it.

Good luck,

Terry

Hello

Assuming that the original number is in column B

Enter this formula in a cell of the same row:

=CNUM(MID($B,1,1))+CNUM(MID($B,2,1))+CNUM(MID($B,3,1))+IF(ISERROR(CNUM(MID($B,4, 1))),0,CNUM(MID($B,4,1)))+IF(ISERROR(CNUM(MID($B,5,1))),0,CNUM(MID($B,5,1)))+IF( ISERROR(CNUM(MID($B,6,1))),0,CNUM(MID($B,6,1)))+IF(ISERROR(CNUM(MID($B,7,1))),0, CNUM(MID($B,7,1)))+IF(ISERROR(CNUM(MID($B,7,1))),0,CNUM(MID($B,8,1)))+IF(ISERROR (CNUM(MID($B,9,1))),0,CNUM(MID($B,9,1)))

It assumes that the number contain at least 3 digits and no more than 9 ones.

It is easy to extand to more digits.
Just paste
+IF(ISERROR(CNUM(MID($B,10,1))),0,CNUM(MID($B,10,1)))
then
+IF(ISERROR(CNUM(MID($B,11,1))),0,CNUM(MID($B,11,1)))
at the very end of the formula.

Yvan KOENIG (from FRANCE vendredi 21 décembre 2007 13:47:46)

If the input number is in A1, try the following. It will handle numbers of basically any size and length without further modification:

=LEN(SUBSTITUTE(SUBSTITUTE(SUBSTITUTE(SUBSTITUTE(SUBSTITUTE(SUBSTITUTE(SUBSTITUT E(SUBSTITUTE(SUBSTITUTE(A1 ,1,".") ,2,"..") ,3,"...") ,4,"....") ,5,".....") ,6,"......") ,7,".......") ,8,"........") ,9,"........."))

(Inspiration for this comes from Douglas Hofstadter's discussion of [Typograhical Number Theory|http://en.wikipedia.org/wiki/Typographical NumberTheory], in +Gödel, Escher, Bach: an Eternal Golden Braid+, an excellent but mentally challenging book.)

Hello

It's WONDERFUL … but as it is it's wrong.

As my daughter discovered, you forgot to replace "0" by an empty string 😉

Yvan KOENIG (from FRANCE vendredi 21 décembre 2007 15:53:55)

There are also examples of Excel formula on the web which you may be able to modify to work in Numbers.

Search for 'sum of digits excel' in a search engine.

Terry

KOENIG Yvan wrote:
As my daughter discovered, you forgot to replace "0" by an empty string 😉

Doh....

For completeness, here is the corrected formula:

=LEN(SUBSTITUTE(SUBSTITUTE(SUBSTITUTE(SUBSTITUTE(SUBSTITUTE(SUBSTITUTE(SUBSTITUT E(SUBSTITUTE(SUBSTITUTE(SUBSTITUTE(A1 ,0,"") ,1,".") ,2,"..") ,3,"...") ,4,"....") ,5,".....") ,6,"......") ,7,".......") ,8,"........") ,9,"........."))

Terry Keelan1 wrote:
There are also examples of Excel formula on the web which you may be able to modify to work in Numbers.

Search for 'sum of digits excel' in a search engine.

Unfortunately, most if not all of these use array forumulas, a feature that is not available in Numbers.