Week 9 – Math 10 – Prime Factorization

Prime Factorization is the process of breaking down a number into a product of prime numbers (numbers that have no factors other than 1 and themselves). A helpful way to find these prime factors is by using factor trees.

Steps for Prime Factorization

  1. Start with the Number: Choose a number you want to factor.
  2. Choose Factors: Think of two numbers that multiply to get that number. Write the number at the top, then draw two branches for the factors.
  3. Repeat Until All Factors are Prime: For each composite (non-prime) factor, keep breaking it down into smaller factors. Stop when all branches lead to prime numbers.
  4. List the Prime Factors: Once all factors are prime, list them.
  5. Combine Like Factors with Exponents: Group any repeating prime factors using exponents to simplify the answer.

Example 1: Prime Factorization of 180

  1. Start: Write 180.
  2. First Split: Choose factors like and .
  3. Continue Factoring:
    • is already prime.
    • Break down into and .
    • is prime.
    • Break 30 down into 1 and .
    • Break 15 into and , which are both prime.
  4. List Prime Factors: , , 3, , and .
  5. Combine with Exponents: 180=2^2⋅3^2⋅5.

Example 2: Prime Factorization of 210

  1. Start: Write .
  2. First Split: Choose factors like and 105.
  3. Continue Factoring:
    • is prime.
    • Break 105 into and 21.
    • 5 is prime.
    • Break 21 into and , both prime.
  4. List Prime Factors: 2, 3, 5, and .
  5. Final Answer: 210=2⋅3⋅5⋅7

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