In 5th Grade Mathematics, prime numbers are numbers that have only two factors: 1 and the number itself. For example, the number 7 is a prime number because it can only be divided by 1 and 7. Prime numbers are important in mathematics because they cannot be divided evenly by any other numbers. Other examples of prime numbers are 2, 3, 5, 11, and 13. It is important to know prime numbers because they play a key role in many mathematical concepts and calculations.