What hides between Shadow and Light?

[mmammel]

If you don't mind, i spent almost all day on a "letter calculator", and I decided to put it on the second page when you insert the letter calculation sheet. I also made a "MOD 9 calculator", put it in the same page.:
Thank you again, I hope we made an useful utility even for other people!

Looks good. A simple function to convert letters to numbers is:
if a letter is in cell A1 for example
=CODE(A1)
will give the ASCII value of the letter. If its a capital letter, just subtract 65 to get a range of 0-25
to get back to a letter from a number
=CHAR(B1+65)
if B1 contains a number 0-25
the mod function is:
=MOD(B3,26)
for mod 26.