When does JMP round probability to 1 or 0?

[#1]

This may be posted somewhere but I can't find it. I have used various distribution functions to determine the probability of a given number in a distribution for many different applications. Sometimes the value is so far off the distribution that the functions return 0 or 1. I was wondering what is the limit where JMP stops and rounds to 0 or 1. That way I can present it as a probability less than what ever that tiny number is and not just say 0. 

[#2]

I don't know when the rounding occurs, but when you encounter a 1 or a 0, double-click that value and change the formatting from Best to Fixed Decimal. Enter a large number like 15 or 20 so that more digits are displayed to see the non-zero (or non-one) result. That typically works.