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Last updated on April 4th, 2025

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Is 328 a Prime Number?

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The numbers that have only two factors, which are 1 and itself, are called prime numbers. For encryption, computer algorithms, and barcode generation, prime numbers are used. In this topic, we will be discussing whether 328 is a prime number or not.

Is 328 a Prime Number? for US Students
Professor Greenline from BrightChamps

Is 328 a Prime Number?

There are two types of numbers, mostly — prime numbers and composite numbers, depending on the number of factors. A prime number is a natural number that is divisible only by 1 and itself. For example, 3 is a prime number because it is divisible by 1 and itself.

 

A composite number is a positive number that is divisible by more than two numbers. For example, 6 is divisible by 1, 2, 3, and 6, making it a composite number. Prime numbers follow a few properties like: -

 

  • Prime numbers are positive numbers always greater than 1. 
  • 2 is the only even prime number. -
  • They have only two factors: 1 and the number itself. -
  • Any two distinct prime numbers are co-prime numbers because they have only one common factor, which is 1.
  • As 328 has more than two factors, it is not a prime number.
Professor Greenline from BrightChamps

Why is 328 Not a Prime Number?

The characteristic of a prime number is that it has only two divisors: 1 and itself. Since 328 has more than two factors, it is not a prime number. A few methods are used to distinguish between prime and composite numbers. These methods include: -

 

  1. Counting Divisors Method 
  2. Divisibility Test 
  3. Prime Number Chart 
  4. Prime Factorization
Professor Greenline from BrightChamps

Using the Counting Divisors Method

The method in which we count the number of divisors to categorize the numbers as prime or composite is called the counting divisors method. Based on the count of the divisors, we categorize numbers as prime or composite. 

 

  • If there is a total count of only 2 divisors, then the number would be prime.
  • If the count is more than 2, then the number is composite.

 

Let’s check whether 328 is prime or composite.

 

Step 1: All numbers are divisible by 1 and themselves.

 

Step 2: Divide 328 by 2. It is divisible by 2, so 2 is a factor of 328.

 

Step 3: Divide 328 by 3. It is not divisible by 3, so 3 is not a factor of 328.

 

Step 4: You can simplify checking divisors up to the square root of 328, which is approximately 18.

 

Step 5: When we divide 328 by 2, 4, 8, and 41, it is divisible by these numbers.

 

Since 328 has more than 2 divisors, it is a composite number.

Professor Greenline from BrightChamps

Using the Divisibility Test Method

We use a set of rules, to check whether a number is divisible by another number completely or not. This is called the Divisibility Test Method. -

 

Divisibility by 2: The number in the ones' place is 8, which is even, meaning that 328 is divisible by 2. 

 

Divisibility by 3: The sum of the digits in the number 328 is 13. Since 13 is not divisible by 3, 328 is also not divisible by 3. 

 

Divisibility by 5: The unit’s place digit is 8. Therefore, 328 is not divisible by 5. 

 

Divisibility by 7: The last digit in 328 is 8. To check divisibility by 7, double the last digit (8 × 2 = 16). Then, subtract it from the rest of the number (32 - 16 = 16). Since 16 is not divisible by 7, 328 is also not divisible by 7. 

 

Divisibility by 11: In 328, the sum of the digits in odd positions is 11, and the sum of the digits in even positions is 2. The difference is 9, which means that 328 is not divisible by 11.

 

Since 328 is divisible by 2 and other factors, it has more than two factors. Therefore, it is a composite number.

Professor Greenline from BrightChamps

Using Prime Number Chart

The prime number chart is a tool created using a method called “The Sieve of Eratosthenes.” In this method, we follow these steps.

 

Step 1: Write 1 to 100 in 10 rows and 10 columns.

 

Step 2: Leave 1 without coloring or crossing it, as it is neither prime nor composite.

 

Step 3: Mark 2 because it is a prime number and cross out all the multiples of 2.

 

Step 4: Mark 3 because it is a prime number and cross out all the multiples of 3.

 

Step 5: Repeat this process until you reach the table consisting of marked and crossed boxes, except 1. Through this process, we will have a list of prime numbers from 1 to 100.

 

Since 328 is larger than 100, we can see it does not appear on the list of prime numbers up to 100, and further analysis shows it is not a prime number.

Professor Greenline from BrightChamps

Using the Prime Factorization Method

Prime factorization is a process of breaking down a number into prime factors. Then multiply those factors to obtain the original number.

 

Step 1: We can write 328 as 2 × 164.

 

Step 2: In 2 × 164, 164 is a composite number. Further, break the 164 into 2 × 82.

 

Step 3: Now break down 82 into 2 × 41.

 

Step 4: 41 is a prime number. Hence, the prime factorization of 328 is 2 × 2 × 2 × 41.

Max Pointing Out Common Math Mistakes

Common Mistakes to Avoid When Determining if 328 is Not a Prime Number

Ray Thinking Deeply About Math Problems

FAQ on is 328 a Prime Number?

1.Is 328 a perfect square?

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2.What is the sum of the divisors of 328?

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3.What are the factors of 328?

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4.What are the closest prime numbers to 328?

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5.What is the prime factorization of 328?

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6.How can children in United States use numbers in everyday life to understand Is 328 a Prime Number??

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7.What are some fun ways kids in United States can practice Is 328 a Prime Number? with numbers?

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8.What role do numbers and Is 328 a Prime Number? play in helping children in United States develop problem-solving skills?

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9.How can families in United States create number-rich environments to improve Is 328 a Prime Number? skills?

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Professor Greenline from BrightChamps

Important Glossaries for "Is 328 a Prime Number"

  • Composite numbers: Natural numbers greater than 1 that are divisible by more than 2 numbers are called composite numbers. For example, 328 is a composite number because it is divisible by 1, 2, 4, 8, 41, 82, 164, and 328.

 

  • Prime numbers: A natural number greater than 1 that has no positive divisors other than 1 and itself.

 

  • Divisibility test: A method to determine if one number is divisible by another without performing actual division.

 

  • Prime factorization: The process of expressing a number as the product of its prime factors.

 

  • Factors: Numbers that divide the original number exactly without leaving a remainder. For example, the factors of 4 are 1, 2, and 4 because they divide 4 completely.
Professor Greenline from BrightChamps

About BrightChamps in United States

At BrightChamps, we know numbers are more than just digits—it’s a way to open doors to countless opportunities! Our mission is to help kids all across the United States grasp important math skills, like today’s focus on the Is 328 a Prime Number? with a special focus on understanding prime numbers—in a way that’s lively, enjoyable, and easy to follow. Whether your child is figuring out how fast a roller coaster speeds through Disney World, keeping track of scores at a Little League baseball game, or managing their allowance to buy the latest gadgets, mastering numbers gives them the confidence they need for everyday challenges. Our interactive lessons make learning both simple and fun. Because kids in the USA learn in many different ways, we tailor our approach to fit each child’s unique style. From the bustling streets of New York City to the sunny shores of California, BrightChamps brings math to life, making it relatable and exciting throughout America. Let’s make prime numbers a fun part of every child’s math journey!
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Hiralee Lalitkumar Makwana

About the Author

Hiralee Lalitkumar Makwana has almost two years of teaching experience. She is a number ninja as she loves numbers. Her interest in numbers can be seen in the way she cracks math puzzles and hidden patterns.

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Max, the Girl Character from BrightChamps

Fun Fact

: She loves to read number jokes and games.

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