To find the probability that Kurt rolls a number less than 5 on a standard 6-sided die, we first identify the total number of outcomes and the successful outcomes.
A standard 6-sided die has the numbers 1, 2, 3, 4, 5, and 6, which gives us a total of 6 possible outcomes.
Next, we determine which of these numbers are less than 5. The numbers that are less than 5 are 1, 2, 3, and 4. Thus, there are 4 successful outcomes.
The probability is calculated using the formula:
\[ \text{Probability} = \frac{\text{Number of successful outcomes}}{\text{Total number of outcomes}} \]
Substituting in the numbers:
\[ \text{Probability} = \frac{4}{6} \]
This fraction can be simplified:
\[ \frac{4}{6} = \frac{2}{3} \]
Therefore, the probability that Kurt rolls a number less than 5 is
\[ \boxed{\frac{2}{3}} \]