Figuring out checksum formula..

I am trying to find a checksum digit...I have the whole formula figured out except fo the last part. I am working with the number 26. How can I find the smallest number which, when added to my number (26), produces a multiple of 10.

basically, that is

26 + x = a multiple of 10 or
26 + x = 30
26 + 4 = 30

Checksum = 4.

So I need excel to figure out which number after 26 is a multiple of 10 (in this case, its 30), and then 30 - 26.

Thanks

I'm not sure if I understand. Is the 26 variable and you want a formula to calculate the checksum? If the variable (26) is in A1 try

=MOD(-A1,10)

Thats it! Thank you so much!

How can I find the number of digits in a cell?

For example, A1 = 0562652

The answer would be 7

Try

=LEN(A1)