# C# Program to Find Prime Factor

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## What is Prime Factor?

A Prime Factors of a given number is that any prime number other than 1 and itself that exactly divides the given number. For example, the prime factors of 60 is 2, 3, 5

## Examples

The following table provides few examples of prime factors of a number.

NumberPrime Factors
555, 11
1002, 5
1862, 3, 31

## Find Prime Factor

In the following example, we will find all the Prime factors of the given number (186).

### Example

C# Compiler
using System; namespace myApp { class Program { static void Main(string[] args) { int num = 186; int i, j; int count = 0; int flag = 0; Console.Write("Prime factor of {0}:\n", num); for(i=2; i<num; i++) { // check for divisibility if(num % i == 0) { count = 0; // check for prime number for(j=1; j<=i; j++) { if(i % j == 0) count++; } if(count == 2) { flag = 1; Console.Write(i +" "); } } } if(flag == 0) Console.Write("There is no Prime factor for {0} ", num); } } }

### Output

Prime factor of 186: 2 3 31

## Find Prime Factor of any Given Number

In the following example, we will find a prime factors of any given number.

### Example

C# Compiler
using System; namespace myApp { class Program { static void Main(string[] args) { Console.Write("Enter a (int) Number: "); int num = Convert.ToInt32(Console.ReadLine()); int i, j; int count = 0; int flag = 0; Console.WriteLine("\nPrime factor of {0}: ", num); for(i=2; i<num; i++) { // check for divisibility if(num % i == 0) { count = 0; // check for prime number for(j=1; j<=i; j++) { if(i % j == 0) count++; } if(count == 2) { flag = 1; Console.Write(i +" "); } } } if(flag == 0) Console.Write("There is no Prime factor for {0} ", num); } } }

### Output

Enter a (int) Number: 25 Prime factor of 25: 5

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