Thank you for your response but my problem is i have to do that for a tons of
worksheet and a lot of formula, so may be it's a bug in excel or may be it's
a configuration problem but if you can help, i'll appreciate
thanks a million

"Bob Umlas, Excel MVP" wrote:

Yes. Instead of using =5.1-5.0, try =ROUND(5.1-5.0,5) or =ROUND(5.1-5.0,8) or
some number of decimal places (under 15!) which you deem sufficient.
Bob Umlas
Excel MVP

"Ohmega" wrote:

When I format the cells in excel as number with more then 15 decimal and i
try to do 5.1 - 5.0 the result is 0.0999999999999996 ...is it normal?