How do we find p(rolling 2 or 5) with one number cube?

The sample space of the rolling the cube is 6.
 The probability of rolling 2 in a cube is 1. So p(2) is 1/6
Similarly the probability of rolling 5 in cube is 1.
 So, p(5) = 1/6
To find p (2 or 5) which is p(2) + p(5)
p(2) + p(5) = 1/6 + 1/6 which is 2/6.
2/6 can be reduced to 1/3.
  so right answer is 1/3

The answer is 1 because you have to flip the sign when dividing by negative number and 3