What is the probability of getting 6 when a dice is thrown twice?

If you only need to get six one time, the probability is 1/6 from the first throw plus 1/6 from the second throw so there is a 2/6 chance or 1/3.

If you need to get six on both throws then there is a 1/6 chance on the first throw and a 1/6 chance on the second so 1/6 times 1/6 is 1/36.

If you want the sum of the two throws to be six then there are 36 possible combinations (1 and 1, 1 and 2, etc.) and five of those add up to six (1 + 5, 2 + 4, 3 + 3, 4 + 2, and 5 + 1) so the probability would be 5/36.