Chapter 6: Problem 63
Write the prime factored form of each number. $$ 18 $$
Short Answer
Expert verified
The prime factors of 18 are \( 2 \times 3^2 \).
Step by step solution
01
Identify the smallest prime number
The smallest prime number is 2. Check if 2 is a factor of 18.
02
Divide by 2
Since 18 is even, divide 18 by 2 to find the quotient. \( 18 \div\ 2 = 9 \)
03
Identify the next smallest prime number
The next smallest prime number is 3. Check if 3 is a factor of 9.
04
Divide by 3
Since 9 can be divided by 3, divide 9 by 3 to find the quotient. \( 9 \div\ 3 = 3 \)
05
Divide by 3 again
Perform the division again since the quotient 3 is also divisible by 3. \( 3 \div\ 3 = 1 \)
06
Write the prime factors
List the prime numbers that were used in the division steps. Prime factors of 18: \( 2 \times 3 \times 3 \) or \( 2 \times 3^2 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Prime Numbers
Prime numbers are the basic building blocks of all numbers. A prime number is a natural number greater than 1 that cannot be formed by multiplying two smaller natural numbers.
In other words, a prime number has exactly two distinct positive divisors: 1 and itself. Examples of prime numbers are:
In other words, a prime number has exactly two distinct positive divisors: 1 and itself. Examples of prime numbers are:
- 2
- 3
- 5
- 7
- 11
Divisibility
Divisibility is the concept of one number being divisible by another without leaving a remainder.
For example, 18 is divisible by 2 because when you divide 18 by 2, you get exactly 9 with no remainder.
Divisibility rules can help you quickly determine if one number is divisible by another. Here are a few rules for smaller prime numbers:
For example, 18 is divisible by 2 because when you divide 18 by 2, you get exactly 9 with no remainder.
Divisibility rules can help you quickly determine if one number is divisible by another. Here are a few rules for smaller prime numbers:
- 2: A number is divisible by 2 if it is even.
- 3: A number is divisible by 3 if the sum of its digits is divisible by 3.
- 5: A number is divisible by 5 if it ends in 0 or 5.
Factorization Step-by-Step
Prime factorization is the process of breaking down a composite number into the prime numbers that multiply to form it. Here is the step-by-step process using the example of 18:
- Step 1: Identify the smallest prime number, which is 2. Check if 2 is a factor of 18.
- Step 2: Since 18 is even, divide it by 2: \(18 \div 2 = 9\).
- Step 3: Identify the next smallest prime number, which is 3. Check if 3 is a factor of 9.
- Step 4: Since 9 can be divided by 3, divide 9 by 3: \(9 \div 3 = 3\).
- Step 5: Perform the division again since the quotient 3 is also divisible by 3: \(3 \div 3 = 1\).
- Step 6: List the prime numbers used in these steps: Prime factors of 18: \[18 = 2 \times 3 \times 3\ or 2 \times 3^2\]