It looks like you meant to type 6/216. This makes sense because in rolling 3 six-sided dice, there are 63 possible outcomes, or 216. Of those 216, only 6 have all 3 numbers matching (111, 222, 333, 444, 555, 666). This 6/216 figure actually reduces to 1/36.
The probability that they do not all match is the probability that you don't get this outcome, or the probability that you get any outcome other than this one. That would mean 1 - 1/36, which is 35/36, or 0.972222.
KHAMP P.
thank you !11/07/19