# Java Program to Calculate the Power of a Number

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## Program to Calculate the Power of a Number

In this article we will see how to calculate the power of a number.

Power of a number is the number raised to that power i.e. when we multiply a number several times to itself.

For example 2^5 = 2*2*2*2*2 = 32

Different methods to do it.

Let’s see one by one.

### Method-1 : Using a For Loop

We can find the power of a number by using a for loop which will iterate over and over until the iterator reaches zero.

Approach:

• We will take the base and the power as input and store them in variables. Also we will initialize the result variable to 1.
• Then we will store the power into an iterator variable.
• Then we will iterate over the loop and keep on multiplying the base to itself.
• Finally we will print the result.

Program:

import java.util.Scanner;
class powerNum{
public static void main(String args[])
{
System.out.println("Enter the base and the power");
//Here we are initializing the number and then
//take them as input
Scanner scan = new Scanner(System.in);
int base = scan.nextInt(), power = scan.nextInt();
long res = 1;

//We will copy the power into the iterators and then run the loop
int i = power;
for (;i != 0; --i)
{
res *= base;
}

//Printing the output
System.out.println("The value of "+base+" raised to the power "+power+" is "+res);
}
}

Output:

Enter the base and the power
2 3
The value of 2 raised to the power 3 is 8

### Method-2 : Using a while Loop

We can find the power of a number by using a while loop which will iterate over and over until the iterator equals the power.

Approach:

• We will take the base and the power as input and store them in variables. Also we will initialize the result variable to 1.
• Then we will set the iterator to 0 and increment it for every iteration.
• For each iteration we will be multiplying the number to itself and storing it in result.
• Finally we will print the result.

Program:

import java.util.Scanner;
class powerNum
{
public static void main(String args[])
{
System.out.println("Enter the base and the power");
//Here we are initializing the number and then
//take them as input
Scanner scan = new Scanner(System.in);
int base = scan.nextInt(), power = scan.nextInt();
long res = 1;

//We will start the loop from 0 and increment it for every iteration
//until it becomes equal to the power
int i = 0;
while(i<power)
{
i++;
res *= base;
}

//Printing the output
System.out.println("The value of "+base+" raised to the power "+power+" is "+res);
}
}

Output:

Enter the base and the power
2 3
The value of 2 raised to the power 3 is 8

### Method-3 : Using recursion

Using recursion we can also get the power of a number.

Approach:

• We will take the base and the power as input and store them in variables.
• Then we will pass the power and base to a recursive function.
• The function will return 1 if the power is 0, or else it will call the same function with decrementing power.
• Finally we will print the result.

Program:

import java.util.Scanner;
class powerNum{
public static int powerCalc(int base, int power)
{
//Recursive Function
if (power == 0)
return 1;
else
return base * powerCalc(base, power - 1);
}

public static void main(String args[])
{
System.out.println("Enter the base and the power");
//Here we are initializing the number and then
//take them as input
Scanner scan = new Scanner(System.in);
int base = scan.nextInt(), power = scan.nextInt(), res;
//Passing the argument into function
res = powerCalc(base, power);

//Printing the output
System.out.println("The value of "+base+" raised to the power "+power+" is "+res);
}
}

Output:

Enter the base and the power
25 5
The value of 25 raised to the power 5 is 9765625

### Method-4 : Using a Library Package

Java has a math library that contains a function called pow( ) which returns the value of the number raised to a certain power.

Approach:

1. We will take the base and the power as input and store them in variables.
2. Then we will pass the power and base to the library function pow( ).
3. The function will return the value which will be stored in another variable.(We will use typecasting to convert the number to int as the library function returns a floating point number)
4. Finally we will print the result.

Program:

import java.util.Scanner;
import java.lang.Math;
class Main
{
public static void main(String args[])
{
System.out.println("Enter the base and the power");
//Here we are initializing the number and then
//take them as input
Scanner scan = new Scanner(System.in);
int base = scan.nextInt(), power = scan.nextInt(), res;
//Passing the argument into function
res = (int)Math.pow(base, power);

//Printing the output
System.out.println("The value of "+base+" raised to the power "+power+" is "+res);
}
}

Output:

Enter the base and the power
2 3
The value of 2 raised to the power 3 is 8

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