What are Prime Numbers?

Hello, Year 6! Today, we’re going to learn about prime numbers. A prime number is a special type of number that can only be divided by 1 and itself. This means it has exactly two distinct positive divisors.

Examples of Prime Numbers

Let’s look at some examples:

  • 2 is a prime number because you can only divide it by 1 and 2.
  • 3 is also a prime number because it can only be divided by 1 and 3.
  • 4 is NOT a prime number because it can be divided by 1, 2, and 4.

Key Rules of Prime Numbers

  1. Two is the only even prime number. All other even numbers can be divided by 2, so they are not prime.
  2. Any number greater than 1 that is not prime is called a composite number. Composite numbers have more than two divisors.
  3. The smallest prime number is 2.

Tips and Tricks to Identify Prime Numbers

  • Check divisibility: Try dividing the number by 2, 3, 5, etc. If it divides evenly (without a remainder), it’s not prime.
  • Use a list: Memorise the first few prime numbers: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97.
  • Remember: If a number ends in 0, 2, 4, 5, 6, or 8 (other than 2), it cannot be prime.

Questions about Prime Numbers

Easy Level Questions

  1. What is the smallest prime number?
  2. Is 5 a prime number? (Yes or No)
  3. List one prime number between 10 and 20.
  4. How many prime numbers are there from 1 to 10?
  5. Is 12 a prime number? (Yes or No)
  6. What two numbers can divide 3?
  7. Is 17 a prime number? (Yes or No)
  8. Write down the first three prime numbers.
  9. Is 15 a prime number? (Yes or No)
  10. Name an even prime number.

Medium Level Questions

  1. How many prime numbers are there between 20 and 30?
  2. Is 29 a prime number? (Yes or No)
  3. What is the next prime number after 31?
  4. Which of the following numbers is prime: 22, 23, 24?
  5. List all prime numbers between 1 and 50.
  6. Is 1 a prime number? (Yes or No)
  7. How can you tell if a number is prime?
  8. What is the sum of the first five prime numbers?
  9. Is 37 a prime number? (Yes or No)
  10. Which number is NOT prime: 41, 42, 43?

Hard Level Questions

  1. Find the prime factorization of 30.
  2. How many prime numbers are between 50 and 100?
  3. What is the largest prime number less than 50?
  4. Is 89 a prime number? (Yes or No)
  5. Create a list of all prime numbers up to 100.
  6. How many prime numbers are there from 1 to 100?
  7. Is 97 a prime number? (Yes or No)
  8. Explain why 4 is not a prime number.
  9. If a number is divisible by 7, can it be prime? (Yes or No)
  10. What is the 10th prime number?

Answers

Easy Level Answers

  1. 2
  2. Yes
  3. 11, 13, 17, 19
  4. 4 (2, 3, 5, 7)
  5. No
  6. 1 and 3
  7. Yes
  8. 2, 3, 5
  9. No
  10. 2

Medium Level Answers

  1. 2 (23, 29)
  2. Yes
  3. 37
  4. 23
  5. 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47
  6. No
  7. Check if it has only two divisors: 1 and itself.
  8. 2 + 3 + 5 + 7 + 11 = 28
  9. Yes
  10. 42

Hard Level Answers

  1. ( 2 \times 3 \times 5 )
  2. 10 (53, 59, 61, 67, 71, 73, 79, 83, 89, 97)
  3. 47
  4. Yes
  5. 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97
  6. 25
  7. Yes
  8. Because it can be divided by 1, 2, and 4.
  9. Yes
  10. 29

I hope this helps you understand prime numbers better! Keep practicing, and soon you’ll be a prime number expert!