> http://freepascal.org/docs-html/rtl/strutils/dec2numb.html > http://freepascal.org/docs-html/rtl/strutils/numb2dec.html This does not solve my problem, I need to use characters from A to Z. Thanks, Silvio Clécio Silvio, read the links, those two functions provide exactly what you want (use BASE 36)