To find the probability of rolling a number greater than 4 on a fair six-sided number cube, we first identify the possible outcomes.
The faces of the cube are numbered from 1 to 6. The numbers that are greater than 4 are 5 and 6.
- Count the total outcomes: There are 6 possible outcomes (1, 2, 3, 4, 5, 6).
- Count the favorable outcomes: The numbers greater than 4 are 5 and 6, which gives us 2 favorable outcomes.
Now we can calculate the probability using the formula:
\[ \text{Probability} = \frac{\text{Number of favorable outcomes}}{\text{Total number of outcomes}} = \frac{2}{6} \]
We can simplify this fraction:
\[ \frac{2}{6} = \frac{1}{3} \]
Thus, the probability of rolling a number greater than 4 is
\[ \boxed{\frac{1}{3}}. \]