A standard number cube (or six-sided die) has the numbers 1 through 6. To find the probability of rolling a prime number, we first identify the prime numbers on the cube.

Prime numbers between 1 and 6 are:

• 2, 3, and 5.

This gives us 3 prime numbers out of the 6 possible outcomes on the cube.

The probability of rolling a prime number is therefore: $\frac{\text{Number of prime numbers}}{\text{Total possible outcomes}} = \frac{3}{6} = \frac{1}{2} = 0.5$

So, the probability of rolling a prime number on a number cube is $\frac{1}{2}$ or 50%.

Would you like more details on probability calculations or have any questions?

Here are five related questions to explore:

1. What is the probability of rolling an even number on a number cube?
2. If two number cubes are rolled, what is the probability that both show a prime number?
3. What is the probability of rolling a composite number on a number cube?
4. How does probability change if we roll a 10-sided die with prime numbers 1 through 10?
5. What is the probability of rolling a prime number or an even number?

Tip: Remember, prime numbers are only divisible by 1 and themselves, making them useful in probability problems for limited outcome sets.