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Last updated on August 30, 2025

Prime Numbers 200 to 400

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The natural numbers greater than 1 are called prime numbers. Prime numbers have only two factors, 1 and the number itself. Besides math, we use prime numbers in many fields, such as securing digital data, radio frequency identification, etc. In this topic, we will learn about the prime numbers 200 to 400.

Prime Numbers 200 to 400 for US Students
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Prime Numbers 200 to 400

A prime number is a natural number with no positive factors other than 1 and the number itself. And the prime number can only be evenly divisible by 1 and the number itself. Here are some basic properties of prime numbers: 

Every number greater than 1 is divisible by at least one prime number. 

Two prime numbers are always relatively prime to each other. 

Every even positive integer greater than 2 can be written as the sum of two prime numbers. 

Every composite number can be uniquely factored into prime factors. 

Except for 2, all prime numbers are odd; 2 is the only even prime number.

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Prime Numbers 200 to 400 Chart

A prime number chart is a table showing the prime numbers in increasing order.

The chart simply includes all the prime numbers within a range for easy identification.

For kids, it will be less difficult to understand the prime numbers through the chart.

The significance of this prime number chart is used in different fields like the foundation of mathematics and the fundamental theorem of arithmetic.

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List of All Prime Numbers 200 to 400

The list of all prime numbers from 200 to 400 provides a comprehensive view of numbers in this range that can only be divided by 1 and the number itself. The prime numbers in the range of 200 to 400 include:

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Prime Numbers - Odd Numbers

Prime numbers and odd numbers are numbers that are only divisible by 1 and the number itself.

They cannot be evenly divisible by 2 or other numbers. 2 is the only even prime number, which divides all the non-prime numbers.

Therefore, except for 2, all prime numbers are considered as the set of odd numbers.

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How to Identify Prime Numbers 200 to 400

Prime numbers are a set of natural numbers that can only be divided by 1 and the number itself. Here are two important ways to find whether a number is prime or not:

 

By Divisibility Method:

To find whether a number is prime or not, we use the divisibility method to check. If a number is divisible by 2, 3, or 5, then it will result in a non-prime number. Prime numbers are only divisible by 1 and themselves. If a number is divisible only by the number itself and 1, it is a prime number. For example: To check whether 307 is a prime number,

 

Step 1: 307 ÷ 2 = 153.5 (remainder ≠ 0)

Step 2: 307 ÷ 3 = 102.33 (remainder ≠ 0)

Step 3: 307 ÷ 5 = 61.4 (remainder ≠ 0)

Since no divisors are found, 307 is a prime number.

 

By Prime Factorization Method:

The prime factorization method is the process of breaking down a composite number into the product of its prime factors. The method of prime factorization helps to identify the prime numbers up to 400 by building the smallest blocks of any given number. For example: The prime factorization of 400: Let's break it down into the smallest prime numbers until it can’t divide anymore.

 

Step 1: 400 ÷ 2 = 200

Step 2: Now, we divide 200, 200 ÷ 2 = 100

Step 3: Now take 100, 100 ÷ 2 = 50

Step 4: Take 50, 50 ÷ 2 = 25

Step 5: At last, take 25, since 25 ends in 5, divide the number with 5 25 ÷ 5 = 5

Step 6: Take 5, 5 ÷ 5 = 1 (since 5 is a prime number, and dividing by 5 gives 1)

Therefore, the prime factorization of 400 is: 400 = 24 × 52.

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Rules for Identifying Prime Numbers 200 to 400

Rule 1: Divisibility Check:

Prime numbers are natural numbers that are greater than 1 and have no divisors other than 1 and the number itself. In the divisibility check rule, we check whether the number is divisible by 2, 3, 5, and 7. If it's divisible by these numbers, then it's not a prime number.

 

Rule 2: Prime Factorization:

In this prime factorization method, we break down all the numbers into their prime factors, showing them as the product of prime numbers.

 

Rule 3: Sieve of Eratosthenes Method:

The method, sieve of Eratosthenes, is an ancient algorithm used to find all prime numbers up to a given limit. First, we list all the numbers from 200 to 400. Then start with the first prime number, 2. Mark all the multiples of 2 as non-prime. Repeat the process for the next unmarked prime number and continue until you reach the square root of 400, approximately 20. The remaining unmarked numbers are the prime numbers.

 

Tips and Tricks for Prime Numbers 200 to 400 

Use common shortcuts to memorize the prime numbers.

Examples include 211, 223, 227, 229, 233, 239, 241, 251, and so on.

Practice using the method of Sieve of Eratosthenes efficiently. Numbers like 210, 220, 230, 240, 250, 260 are never prime.

Knowing the common multiples of numbers helps in avoiding unnecessary checks.

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Common Mistakes and How to Avoid Them in Prime Numbers 200 to 400

While working with the prime numbers 200 to 400, children might encounter some errors or difficulties. We have many solutions to resolve those problems. Here are some given below:

Mistake 1

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Confusing composite numbers with prime numbers.

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A prime number has exactly 2 divisors: 1 and the number itself. Remember that composite numbers have more than 2 divisors.

 

For example, 221 is not a prime number because it has more than 2 divisors.

Mistake 2

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Including 1 as a prime number.

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Always remember that primes are greater than 1. 1 is not a prime number because it has only one divisor, itself.

Mistake 3

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Not efficiently using the prime checking method.

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Practice using the method of Sieve of Eratosthenes efficiently or check divisibility by primes up to the square root of the number.

 

For example, while checking the divisibility of 361, stop once you reach √361.

Mistake 4

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Not realizing about the primes in the larger prime range.

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Keep on practicing identifying the larger primes, as it helps to sharpen the skills of children. The usage of the method of Sieve of Eratosthenes helps to solve this.

Mistake 5

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Forgetting that multiples of any prime number are not prime.

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Erase all the multiples of known prime numbers as soon as possible.

 

For example, if you're checking numbers up to 400, you don't have to check numbers divisible by 2, 3, 5, or 7 because they are not prime.

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Prime Numbers Examples

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Problem 1

Is 373 a prime number?

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Yes, 373 is a prime number.

Explanation

The square root of 373 is approximately 19.31.

We check divisibility by primes less than 19.31 (2, 3, 5, 7, 11, 13, 17, 19).

373 ÷ 2 = 186.5

373 ÷ 3 = 124.33

373 ÷ 5 = 74.6

373 ÷ 7 = 53.2857

373 ÷ 11 = 33.909

Since 373 is not divisible by any of these numbers, 373 is a prime number.

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Problem 2

Amanda needs a password for her secure file, and the password is the largest prime number under 400. Which prime number should she use?

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397 is the largest prime number under 400, so Amanda should use 397.

Explanation

Prime numbers are natural numbers that are greater than 1 and have no divisors other than 1 and the number itself.

The prime numbers under 400 are 200, 201, 203, and so on.

397 is the largest prime number under 400, therefore the password should be 397.

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Problem 3

A teacher challenges her students: Find the prime numbers that are closest to 250 but less than 250.

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241 is the prime number closest to 250.

Explanation

241 is a prime number because it is only divisible by 1 and the number itself.

And the next prime number after 241 is 251, which is greater than 250.

Therefore, the prime number closest to 250 and less than 250 is 241.

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FAQs on Prime Numbers 200 to 400

1.Give some examples of prime numbers.

Examples of prime numbers include 211, 223, 227, 229, 233, 239, 241, 251, and so on.

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2.Explain prime numbers in math.

Prime numbers are natural numbers that have only 1 and the number itself as factors. They cannot be divided by any other numbers. For example, 223, 227, 229, 233, 239, and so on.

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3.Is 2 the smallest prime number?

Yes, 2 is the smallest prime number. Also, 2 is the only even prime number in mathematics.

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4.Which is the largest prime number?

There is no largest prime number because primes are infinite.

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5.Which is the largest prime number between 200 and 400?

The largest prime number between 200 and 400 is 397.

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Important Glossaries for Prime Numbers 200 to 400

  • Prime numbers: The natural numbers which are greater than 1 and that are divisible by 1 and the number itself. For example, 211, 223, 227, 229, 233, 239, and so on.

 

  • Odd numbers: Numbers that are not divisible by 2 are called odd numbers. All prime numbers except 2 are odd. For example, 3, 5, 7, 11, 13, and so on.

 

  • Composite numbers: Composite numbers are non-prime numbers that have more than 2 factors. For example, 12 is a composite number, and it is divisible by 1, 2, 3, 4, 6, and 12.

 

  • Divisibility: A method to check if one number is divisible by another without leaving a remainder. If a number can only be divided by 1 and itself, it is a prime number.

 

  • Sieve of Eratosthenes: An ancient algorithm used to find all prime numbers up to a given limit by systematically marking the multiples of each prime number starting from 2.
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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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Fun Fact

: She loves to read number jokes and games.

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