1. Multiply a number with 2 ^n

2. Check if a number is power of 4 or not

## 1. Multiply a number with 2 ^n

The solution is very simple. We know the left shift operator is a 2 raised to the power of n.

Hence we do num << n, should give us the expected result.

## 2. Check if a number is power of 4 or not

Here we check the number of zero’s before the set bit. If the number of 0’s are even then it is a power of 4 else not.

Example:

16 in binary 10000

The number of 0’s is even before the set bit “1”. Hence it is a power of 4.

## Solution in C++

#include<iostream> #include<vector> #include<string> using namespace std; void multiply_2_n(int num, int n) { cout<<"The number "<<num<< " raised to 2 power of "<<n<<" is = "<< (num <<n)<<endl; } void check_num_power_of_4(int num) { int count = 0; if ( num && !(num&(num-1)) ) { while(num > 1) { num >>= 1; count += 1; } } if (count%2 == 0) cout<<"The number is a power of 4"<<endl; else cout<<"The number is not a power of 4"<<endl; } int main() { int num = 16; int n = 2; multiply_2_n(num, n); check_num_power_of_4(num); return 0; }

## Output:

The number 16 raised to 2 power of 2 is = 64 The number is a power of 4