# how to find factorial in java

#### how to find factorial in java

In this article, we will learn how to find the factorial of a number in java. The factorial of a number is the product of all the integers from 1 to that number.

Factorial of a non-negative integer, is multiplication of all integers smaller than or equal to n. For example factorial of 6 is 6*5*4*3*2*1 which is 720.

We will implement 5 Different Ways to find the factorial number in java.

E.g:

1. Java Program Using For Loop
2. Using Command Line Arguments
3. Using Function
4. Using Recursion
5. Using while loop

Example 1:

Java Program To Calculate Factorial using standard values with outputs

Standard values – consider the following code is universally applicable- with sample outputs.

Method 1: Java Program To Calculate Factorial using standard values with outputs

class Factoral
{
public static void main(String arg[])
{
int n=5,fact=1;

``````        for(int i=1;i<=n;i++)
{

fact=fact*i;
}

System.out.println("factoral="+fact);
}``````

}

Output:

factorial = 120

Example 2:

Java Program Using For Loop

Among all three loops, for loop is probably the most used loop. For loop are two types mainly:

1. for each style of for loop
2. normal for loop

Method 2: Java Program Using For Loop
``````class Factorial
{
public static void main(String arg[])

{

long n,fact=1;

Scanner sc=new Scanner(System.in);

System.out.println("enter number");

n=sc.nextLong();

for(int i=1;i<=n;i++)
{

fact=fact*i;

}

System.out.println("fact="+fact);

}

}``````

Output:

enter number
7 = 5040

Example 3:

Using Command Line Arguments

Method 3: Using Command Line Arguments
``````import java.util.Scanner;
class Factorl
{
public static void main(String args[])

{
long n,fact=1;

n=Long.parseLong(args);

for(int i=1;i<=n;i++)
{
fact=fact*i;
}

System.out.println("fact="+fact);
}
}``````

Output:

Java Factorl 9
fact = 362880

Example 4:

Using Function

Method 4: Using Function
``````import java.util.Scanner;
class Factorl
{
public static void main(String args[])

{

long n,fact=0;

n=Long.parseLong(args);

fact=factCal(n);

System.out.println("fact="+fact);

}

static long factCal(long x)
{
long fact=1;
for(int i=1;i<=x;i++)
{

fact=fact*i;

}
return fact;
}

}``````

Output:

java Factorl 10

fact = 3628800

Example 5:

Using Recursion

Recursion: A Recursion is a function call itself – you can check out more information about what is recursion in java here?

Method 5 Using Recursion
``````class Factorl
{
public static void main(String arg[])
{
long n;

Scanner sc=new Scanner(System.in);

System.out.println("enter number");

n=sc.nextLong();

long f=Factorl.fact(n);

System.out.println("factorial="+f);
}

static long fact(long n)
{
if(n<=0)
return 1;

return Factorl.fact(n-1)*n;
}
}``````

Output:

enter number

30

Factorl=8764578968847253504

Example 6:

Using while loop

Method 6 Using while loop
``````import java.util.Scanner;

class Factrl
{
public static void main(String arg[])

{

long n,fact=1;

Scanner sc=new Scanner(System.in);

System.out.println("enter number");

n=sc.nextLong();
int i=1;
while(i<=n)
{

fact=fact*i;
i++;
}

System.out.println("fact="+fact);

}
}``````

Output:

enter number
10
fact=3628800

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