Prime Factorization - Examples, Exercises and Solutions

Understanding Prime Factorization

Complete explanation with examples

Prime Factorization

Prime factorization (or prime decomposition) consists of breaking down a certain number into prime numbers, called factors, whose product (multiplication) results in the original number.

The first method - Factor tree method

Let's take the number we want to factorize and draw 22 branches from it.
We will ask ourselves, which 22 numbers can we find whose multiplication results in this same number, except for the original number and 11.
Let's see if the numbers we found are prime or composite, we will break down the composite ones into two branches again.
We will continue breaking down all the composite numbers until we only have primes, which we will mark with a circle.

The second method - Split Window Method

Let's write the number we want to factorize on the left side of a vertical line that acts as a division window.
Let's look for the smallest prime number by which we can divide the original, we write it on the right side of the line and the result we write on the left, below the first one. We will continue in this manner until we reach the number 11 and finish the exercise.
All the prime numbers will appear on the right side of the dividing line.

Visual comparison of two methods for prime factorization of 100: factor tree method and division method, both resulting in 2 × 2 × 5 × 5

Detailed explanation

Practice Prime Factorization

Test your knowledge with 8 quizzes

Write all the factors of the following number: \( 99 \)

Examples with solutions for Prime Factorization

Step-by-step solutions included
Exercise #1

Write all the factors of the following number: 7 7

Step-by-Step Solution

To determine all the factors of the number 7, we will examine which integers between 1 and 7 divide it exactly:

  • Check 1: Since 71=7 \frac{7}{1} = 7 , 1 is a factor.
  • Check 2: 72=3.5 \frac{7}{2} = 3.5 , which is not an integer, so 2 is not a factor.
  • Check 3: 732.333 \frac{7}{3} \approx 2.333 , which is not an integer, so 3 is not a factor.
  • Check 4: 74=1.75 \frac{7}{4} = 1.75 , which is not an integer, so 4 is not a factor.
  • Check 5: 75=1.4 \frac{7}{5} = 1.4 , which is not an integer, so 5 is not a factor.
  • Check 6: 761.167 \frac{7}{6} \approx 1.167 , which is not an integer, so 6 is not a factor.
  • Check 7: Since 77=1 \frac{7}{7} = 1 , 7 is a factor.

Therefore, the factors of 7 are 1 1 and 7 7 .

These results correspond to choice 1: 1,7 1, 7 .

Answer:

No prime factors

Video Solution
Exercise #2

Write all the factors of the following number: 6 6

Step-by-Step Solution

To determine the factors of the number 6 6 , we will follow these steps:

  • Step 1: Begin by checking each number starting from 1 1 up to 6 6 to see if it divides 6 6 evenly.

  • Step 2: Check 1 1 . Since 1×6=6 1 \times 6 = 6 , 1 1 is a factor.

  • Step 3: Check 2 2 . Since 2×3=6 2 \times 3 = 6 , 2 2 is a factor.

  • Step 4: Check 3 3 . Since 3×2=6 3 \times 2 = 6 , 3 3 is a factor.

  • Step 5: Check 4 4 . Since 6 6 is not evenly divisible by 4 4 , 4 4 is not a factor.

  • Step 6: Check 5 5 . Since 6 6 is not evenly divisible by 5 5 , 5 5 is not a factor.

  • Step 7: Finally, check 6 6 . Since 6×1=6 6 \times 1 = 6 , 6 6 is a factor.

All possible whole number products (pairs) that result in 6 6 are 1×6 1 \times 6 , 2×3 2 \times 3 , 3×2 3 \times 2 , and 6×1 6 \times 1 .

However, when checking for unique prime factors as a particular approach in factors identification, 6 6 breaks down into prime factors of 2 2 and 3 3 .

Therefore, the primary distinct prime factors of 6 6 are 2 2 and 3 3 .

This correlates with choice 3:

  • Choice 3 3 : 2,3 2,3 , which matches our factors.

Thus, the answer is correctly represented as the distinct prime factors 2,3 2, 3 in the context of the problem requirements.

Answer:

2,3 2,3

Video Solution
Exercise #3

Write all the factors of the following number: 9 9

Step-by-Step Solution

To find all the factors of 9, we will determine the divisors of the number 9 by testing each integer from 1 up to 9.

  • Step 1: Test if 1 is a factor of 9. Since 9÷1=9 9 \div 1 = 9 , 1 is a factor.
  • Step 2: Test if 2 is a factor of 9. Since 9÷2=4.5 9 \div 2 = 4.5 (not an integer), 2 is not a factor.
  • Step 3: Test if 3 is a factor of 9. Since 9÷3=3 9 \div 3 = 3 , 3 is a factor.
  • Step 4: Test if 4 is a factor of 9. Since 9÷4=2.25 9 \div 4 = 2.25 (not an integer), 4 is not a factor.
  • Step 5: Test if 5 is a factor of 9. Since 9÷5=1.8 9 \div 5 = 1.8 (not an integer), 5 is not a factor.
  • Step 6: Test if 6 is a factor of 9. Since 9÷6=1.5 9 \div 6 = 1.5 (not an integer), 6 is not a factor.
  • Step 7: Test if 7 is a factor of 9. Since 9÷71.2857 9 \div 7 \approx 1.2857 (not an integer), 7 is not a factor.
  • Step 8: Test if 8 is a factor of 9. Since 9÷8=1.125 9 \div 8 = 1.125 (not an integer), 8 is not a factor.
  • Step 9: Test if 9 is a factor of 9. Since 9÷9=1 9 \div 9 = 1 , 9 is a factor.

The factors of 9 are 1, 3, and 9.

However, the problem might specifically be asking for the prime factorization where the number 9 decomposes into 3×3 3 \times 3 .

Therefore, the correct answer which matches the provided choices is 3,3 3, 3 .

Answer:

3,3 3,3

Video Solution
Exercise #4

Write all the factors of the following number: 8 8

Step-by-Step Solution

To find the factors of 8, we'll use prime factorization.

  • Step 1: Begin with the smallest prime number, 2.
  • Step 2: Divide 8 by 2, which gives 4. Since 4 is even, divide by 2 again.
  • Step 3: Divide 4 by 2, which gives 2. Divide 2 by 2 one more time.
  • Step 4: This yields 1, so we've fully factored the number.

Thus, the prime factorization of 8 is 2×2×2 2 \times 2 \times 2 .

The factors of the number 8 are 2,2,2 2, 2, 2 .

Therefore, the correct answer is choice 4: 2,2,2 2, 2, 2 .

Answer:

2,2,2 2,2,2

Video Solution
Exercise #5

Write all the factors of the following number: 4 4

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Identify all the factors of the number 4.
  • Determine which of these factors are prime numbers.
  • Check the answer choices to find the one that corresponds to the prime factorization of 4.

Now, let's work through each step:
Step 1: To find the factors of 4, we consider pairs of numbers that multiply to 4, such as 1×4 1 \times 4 and 2×2 2 \times 2 .
Step 2: Among these factors, identify the prime numbers. The number 2 is the only prime factor, and it needs to be listed twice since 2×2=4 2 \times 2 = 4 .
Step 3: Looking at the answer choices, the choice that corresponds to the prime factorization of 4 is 2,2 2, 2 .

Therefore, the correct answer is 2,2 2, 2 .

Answer:

2,2 2,2

Video Solution

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