What is th probability of rolling six three times in a row with a six sided dice?

Assuming that the die is a "normal" one (it has the numbers 1 to 6 and that it is fair), then the probability of rolling six three times in a row is 1/6*1/6*1/6 = 1/216 = 0.00463

The probability of rolling six three times in a row eventually is 1 (ie a certainty).