Multiply a given Integer with 3.5

Given a integer x, write a function that multiplies x with 3.5 and returns the integer result. You are not allowed to use %, /, *.

Examples :
Input: 2
Output: 7

Input: 5
Output: 17 (Ignore the digits after decimal point)

Solution:
1. We can get x*3.5 by adding 2*x, x and x/2. To calculate 2*x, left shift x by 1 and to calculate x/2, right shift x by 2.

C++

// C++ program to multiply 
// a number with 3.5 
#include <bits/stdc++.h> 
  
int multiplyWith3Point5(int x) 
{ 
    return (x<<1) + x + (x>>1); 
}  
  
/* Driver program to test above functions*/
int main() 
{ 
    int x = 4;  
    printf("%d", multiplyWith3Point5(x)); 
    getchar(); 
    return 0; 
} 

Java

// Java Program to multiply 
// a number with 3.5 
  
class GFG { 
          
    static int multiplyWith3Point5(int x) 
    { 
        return (x<<1) + x + (x>>1); 
    }  
      
    /* Driver program to test above functions*/
    public static void main(String[] args) 
    { 
        int x = 2;  
        System.out.println(multiplyWith3Point5(x)); 
    } 
} 
  
// This code is contributed by prerna saini. 

Python3

# Python 3 program to multiply 
# a number with 3.5 
  
def multiplyWith3Point5(x): 
  
    return (x<<1) + x + (x>>1) 
   
  
# Driver program to  
# test above functions 
x = 4 
print(multiplyWith3Point5(x)) 
  
# This code is contributed by 
# Smitha Dinesh Semwal 

C#

// C# Program to multiply 
// a number with 3.5 
using System; 
  
class GFG 
{ 
          
    static int multiplyWith3Point5(int x) 
    { 
        return (x<<1) + x + (x>>1); 
    }  
      
    /* Driver program to test above functions*/
    public static void Main() 
    { 
        int x = 2;  
        Console.Write(multiplyWith3Point5(x)); 
    } 
      
} 
  
// This code is contributed by Sam007 

PHP

<?php 
// PHP program to multiply 
// a number with 3.5 
  
  
function multiplyWith3Point5( $x) 
{ 
    return ($x << 1) + $x + ($x >> 1); 
}  
  
// Driver Code 
$x = 4;  
echo multiplyWith3Point5($x); 
      
// This code is contributed by vt_m. 
?> 

2. Another way of doing this could be (8*x – x)/2 (See below code). Thanks to Ajaym for suggesting this.

#include <stdio.h> 
int multiplyWith3Point5(int x) 
{ 
  return ((x<<3) - x)>>1; 
}     

Please write comments if you find the above code/algorithm incorrect, or find better ways to solve the same problem

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My Personal Notes

C++

Java

Python3

C#

PHP

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