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Last updated on May 26th, 2025

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Is 105 a Prime Number?

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A number is classified as a prime number if it satisfies a certain condition. The number has to be having only two factors 1 and the number itself, all other numbers which have more than two factors are categorized under composite numbers. The prime are used in our everyday life for the security and pin encryption and in machinery building.

Is 105 a Prime Number? for US Students
Professor Greenline from BrightChamps

Is 105 a prime number?

A prime number should not have factors more than 2 but 105 has 4 divisors. No, 105 is a composite number. 


The divisors of 105 are 1, 3, 5, 7, 15, 21, 35, and 105.  Therefore, 105 is a composite number. Composite numbers are the numbers which have factors more than 2.

 

is 105 a prime number
 

Professor Greenline from BrightChamps

Why is 105 a prime number?

A number to be a prime number should follow the criteria, which is that it should not have factors more than 2. 105 has factors more than 2, so it is a composite number.


Given below are a few ways that can be used to find prime or composite numbers.

Professor Greenline from BrightChamps

Using the Counting Divisors Method

In this method, the divisors of a number are listed, and the number is checked, to be called a prime number. The counting divisors method for 105 would simply be


Divisors of 105 = 1, 3, 5, 7, 15, 21, 35, 105


Number of divisors = 8


The number 105 can be considered composite.
 

Professor Greenline from BrightChamps

Using the Divisibility Test Method

In divisibility method, the prime number only has 2 divisors, which are 1 and itself.


Divisors of 105 = 1, 3, 5, 7, 15, 21, 35, 105


As 105 has factors more than 2 then it is not a prime number
 

Professor Greenline from BrightChamps

Using Prime Number Chart

We write the prime number chart up to 10, which helps in sorting numbers.


The prime numbers from 100 to 200 are 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199. 105 is not on the list, so it is not a prime number.
 

Professor Greenline from BrightChamps

Using the Prime Factorization Method

This method is only used for a composite number. Since 105 is a composite number, prime factorization for 105 is: 31 x 51 x 71


Hence, the prime factors of 105 are 3, 5, and 7.

Max Pointing Out Common Math Mistakes

Common Mistakes to Avoid When Determining if 105 is a Prime Number.

It is common to make mistakes while learning the prime numbers, and children while learning prime numbers for the first time it is mostly certain to happen. The mistakes and the solution given below will help you in getting an idea on where all mistakes might be made and how to avoid them.
 

Mistake 1

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 Not considering 1 as a factor.

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Students might not count 1 as a factor, and will mostly skip it, which results in wrong count of factors.
 

Ray Thinking Deeply About Math Problems

FAQs for “Is 105 a Prime Number”

1. What is expressed as a product of prime factors 105?

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2.Why 105 is not a prime number?

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3. Is 105 divisible by 3?

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4.What is the multiple of 105?

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5.What are common number factors?

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6.How can children in United States use numbers in everyday life to understand Is 105 a Prime Number??

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7.What are some fun ways kids in United States can practice Is 105 a Prime Number? with numbers?

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8.What role do numbers and Is 105 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 105 a Prime Number? skills?

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Professor Greenline from BrightChamps

Important Glossaries for "Is 105 a Prime Number"

  • Divisibility: The property of a number which can divide another number completely without leaving any remainder.

 

  • Chart of Prime Numbers: The numbers which has only two factors are listed together.

 

  • Composite Number: A number that has more than two positive divisors which are opposite to prime numbers which has only two factors.
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 105 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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