Multiply any Number with 4 using Bitwise Operator

We are a Number n and our task is to multiply the number by 4 using a bit-wise Operator.

Examples: 

Input : 4
Output :16

Input :5
Output :20

Explanation Case 1:- n=4 the binary of 4 is 100 and now shifts two bit right then 10000 now the number is 16 is multiplied 4*4=16 ans. 
Approach :- (n<<2) shift two bit right

C++

// C++ program to multiply a number with
// 4 using Bitwise Operator
#include <bits/stdc++.h>
using namespace std;

// function the return multiply a number
//  with 4 using bitwise operator
int multiplyWith4(int n)
{
    // returning a number with multiply
    // with 4 using2 bit shifting right
    return (n << 2);
}

// derive function
int main()
{
    int n = 4;
    cout << multiplyWith4(n) << endl;
    return 0;
}

Java

// Java program to multiply a number
// with 4 using Bitwise Operator

class GFG {

// function the return
// multiply a number
// with 4 using bitwise
// operator
static int multiplyWith4(int n)
{

    // returning a number
    // with multiply with
    // 4 using 2 bit shifting
    // right
    return (n << 2);
}

// Driver Code
public static void main(String[] args)
{
    int n = 4;
    System.out.print(multiplyWith4(n));
}
}

// This code is contributed by Smitha.

Python 3

# Python 3 program to multiply
# a number with 4 using Bitwise
# Operator

# function the return multiply
# a number with 4 using bitwise
# operator
def multiplyWith4(n):

    # returning a number with
    # multiply with 4 using2
    # bit shifting right
    return (n << 2)

# derive function
n = 4
print(multiplyWith4(n))

# This code is contributed
# by Smitha

C#

// C# program to multiply a number
// with 4 using Bitwise Operator
using System;

class GFG {

// function the return
// multiply a number
// with 4 using bitwise
// operator
static int multiplyWith4(int n)
{

    // returning a number
    // with multiply with
    // 4 using 2 bit shifting
    // right
    return (n << 2);
}

// Driver Code
public static void Main(String[] args)
{
    int n = 4;
    Console.Write(multiplyWith4(n));
}
}

// This code is contributed by Smitha.

PHP

<?php
// PHP program to multiply
// a number with 4 using
// Bitwise Operator

// function the return
// multiply a number
// with 4 using bitwise
// operator
function multiplyWith4($n)
{

    // returning a number
    // with multiply with
    // 4 using2 bit
    // shifting right
    return ($n << 2);
}

    // Driver Code
    $n = 4;
    echo multiplyWith4($n),"\n";

// This code is contributed by Ajit.
?>

Javascript

<script>
// javascript program to multiply a number
// with 4 using Bitwise Operator
// function the return
// multiply a number
// with 4 using bitwise
// operator
function multiplyWith4(n)
{

    // returning a number
    // with multiply with
    // 4 using 2 bit shifting
    // right
    return (n << 2);
}

// Driver Code
var n = 4;
document.write(multiplyWith4(n));

// This code is contributed by Amit Katiyar
</script>

Output

16

Time Complexity: O(1)
Auxiliary Space: O(1)

Generalization : In general, we can multiply with a power of 2 using bitwise operators. For example, suppose we wish to multiply with 16 (which is 2⁴), we can do it by left shifting by 4.