What are Prime Numbers? | Math with Mr. J

Summary

In this educational video, Mr. J explains the concept of prime numbers, emphasizing that they are whole numbers with only two factors: 1 and the number itself. He walks through examples like 3, 7, 19, and 2, demonstrating how to identify prime numbers. He also clarifies composite numbers by showing that numbers like 21 and 8 have more than two factors. The video highlights that all even numbers, except 2, are automatically composite. The lesson offers a clear, engaging introduction to prime numbers and their characteristics, helping viewers distinguish between prime and composite numbers.

Takeaways

• 😀 Prime numbers are whole numbers greater than 1 with exactly two factors: 1 and the number itself.
• 😀 3 is prime because its only factors are 1 and 3.
• 😀 7 is prime because its only factors are 1 and 7.
• 😀 19 is prime because its only factors are 1 and 19.
• 😀 2 is the only even prime number, as its only factors are 1 and 2.
• 😀 21 is not prime because its factors include 1, 3, 7, and 21.
• 😀 13 is prime because its only factors are 1 and 13.
• 😀 8 is not prime because its factors include 1, 2, 4, and 8.
• 😀 5,462 is not prime because it is an even number, and all even numbers (except 2) are composite.
• 😀 Prime numbers have only two factors, while composite numbers have more than two factors.

Q & A

What is a prime number?

A prime number is a whole number with exactly two factors: 1 and the number itself.

Can you give an example of a prime number?

Yes, 3 is an example of a prime number because its only factors are 1 and 3.

Why is 2 considered a unique prime number?

2 is the only even prime number because its only factors are 1 and 2. All other even numbers are not prime.

What makes a number composite rather than prime?

A number is considered composite if it has more than two factors. For example, 21 has factors of 1, 3, 7, and 21, so it is composite.

Is 13 a prime number?

Yes, 13 is a prime number because its only factors are 1 and 13.

Why is 8 not a prime number?

8 is not a prime number because it has more than two factors: 1, 2, 4, and 8.

Why is 5462 not a prime number?

5462 is not a prime number because it is even, and all even numbers (except 2) are not prime. Since 5462 is divisible by 2, it is composite.

What does the term 'factors' mean in relation to numbers?

Factors are the numbers that can be multiplied together to give another number. For example, the factors of 6 are 1, 2, 3, and 6.

What is the significance of knowing a number's factors when determining if it is prime?

Knowing a number's factors helps determine if it is prime. If the only factors are 1 and the number itself, it is prime. If there are additional factors, it is composite.

Can an even number ever be prime other than 2?

No, 2 is the only even prime number. All other even numbers are divisible by 2 and thus are not prime.