Is 942 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 942 has more than two factors, it is not a prime number.
  

The characteristic of a prime number is that it has only two divisors: 1 and itself. Since 942 has more than two factors, it is not a prime number. Several methods are used to distinguish between prime and composite numbers. A few methods are: 

• Counting Divisors Method
   
• Divisibility Test 
   
• Prime Number Chart 
   
• Prime Factorization

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 942 is prime or composite.

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

Step 2: Divide 942 by 2. It is divisible by 2, so 2 is a factor of 942.

Step 3: Divide 942 by 3. It is divisible by 3, so 3 is a factor of 942.

Step 4: You can simplify checking divisors up to 942 by finding the square root value. We then need to only check divisors up to the root value.

Since 942 has more than 2 divisors, it is a composite number.

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 value is 2. Since 2 is an even number, 942 is divisible by 2.

Divisibility by 3: The sum of the digits in the number 942 is 15. Since 15 is divisible by 3, 942 is also divisible by 3.

Divisibility by 5: The unit’s place digit is 2. Therefore, 942 is not divisible by 5. 

Divisibility by 7: Doubling the last digit (2 × 2 = 4) and subtracting it from the rest of the number (94 - 4 = 90) shows that 90 is divisible by 7, so 942 is also divisible by 7.

Divisibility by 11: The difference between the sum of the digits in odd positions (9 + 2 = 11) and even positions (4) is 7, which is not divisible by 11, so 942 is not divisible by 11.

Since 942 is divisible by 2, 3, and 7, it has more than two factors. Therefore, it is a composite number.

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

Step 1: Write numbers up to 1000 in rows and columns.

Step 2: Leave 1 without coloring or crossing, 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.

942 is not present in the list of prime numbers, so it is a composite number.

Prime factorization is a process of breaking down a number into prime factors, then multiplying those factors to obtain the original number.

Step 1: We can write 942 as 2 × 471.

Step 2: In 2 × 471, 471 is a composite number. Further, break 471 into 3 × 157.

Step 3: Now we get the product consisting of only prime numbers.

Hence, the prime factorization of 942 is 2 × 3 × 157.

• Composite numbers: Natural numbers greater than 1 that are divisible by more than 2 numbers. For example, 12 is a composite number because it is divisible by 1, 2, 3, 4, 6, and 12. 
   
• Prime numbers: Numbers greater than 1 that have no divisors other than 1 and themselves, such as 3, 5, and 7. 
   
• Divisibility rules: Guidelines used to determine if one number is divisible by another without performing division.
   
• Prime factorization: The process of expressing a number as the product of its prime factors. 
   
• Sieve of Eratosthenes: An ancient algorithm used to find all prime numbers up to any given limit.