I apologize for posting a question to the wrong mailing list. I'm relying on the generosity and understanding of the subscribers. I've no experience of programming in Tcl language. Today I was shown the wierd behaviour of a Tcl/Tk GUI and asked to help fix the following problem. Basically a parameter representing a scale factor is entered through the keyboard. If the entered value is less than 10^10 then the program behaviour is correct. If the entered value exceeds 10^10 then no error is eturned but the interface behaviour is not correct as the scaling factor is not correctly applied. Questions: 1) is there a maximum value that can be represented ? 2) if the answer to 1) is "yes" then is 10^10 the maximum value that can be stored in a variable ? 3) if the answers to both 1) and 2) is "yes" then is it possible to deal with values greater than 10^10 ? How ? Thank you very much for your help. Maura