Topic 5-2 Prime Factorization I can label a number as prime or composite. I can write numbers as a product of their prime factors. CAKE METHOD TREE METHOD

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Lesson Vocabulary I say, you say, we clap Prime Number Has EXACTLY two factors, 1 and itself. Can you name the ONLY even prime number? 2, 3, 5 are examples of prime numbers 6, 10 and 14 are NOT prime

Sieve of Eratosthenes

Lesson Vocabulary I say, you say, we clap Composite Number Has MORE than two factors and can be written as the product of its prime factors 6, 10 and 14, 15 ARE composite 2, 3, 5, are NOT composite

Quick Write Directions for building things, recipes for cooking are often broken into simpler parts. (Step 1, Step 2, etc.) Why is this helpful? Write for 1 minute. Turn to your partner and share what you wrote.

Products and Factors Write 24 as a multiplication problem as many ways as possible. Work with your partner to get as many answers as possible. Circle the factors and underline the product in your answers.

Prime Factorization Prime Factorization is a number written as a product of all its prime factors. 24 = 2 x 2 x 2 x 3 or 2 x 3 2 ways to find prime factorization are the cake method and the tree method. 3

6. Write 24 as the product of all its prime numbers Tree Method 1. Make a “tree” 2. Pick the smallest prime number that it is divisible by. 3. If the other factor is prime, circle it 4. If the other factor is composite, make another “tree” 5. Repeat the process until both factors are prime 24 2 12 2 6 6. Write 24 as the product of all its prime numbers 2 x 2 x 2 x 3 Or 2 x 3 2 3 3

Cake Method List the first 5 prime numbers along the side of your paper Start with the SMALLEST prime number that will go into the number Put the quotient underneath Repeat, always using the smallest possible prime number as a the divisor until you get a prime number as your quotient. 2 3 5 7 11 2 24 2 12 2 6 3 List all of the numbers along the left side and the last bottom one as the prime factorization. 2 x 2 x 2 x 3 Or 2 x 3 3

Try It! With your partner, find the prime factorization of the following numbers. Take turns using the cake method and the tree method. 26 27 65 72

Which method do you like the best? Why? CAKE METHOD TREE METHOD