There are 6 ways we can roll doubles out of a possible 36 rolls (6 x 6), for a probability of 6/36, or 1/6, on any roll of two fair dice. So you have a 16.7% probability of rolling doubles with 2 fair six-sided dice.
Second Answer : 6/36
Out of the 6^2 = 36 outcomes, there is only 6 that are doubles (double 1,double 2,… double 6). Therefore the probability is 6/36 i 1/6.