In this tutorial, the power of 2 or not for python programming can be checked. The user gives a positive integer N and we have to check if it is equivalent to 2^x or not, where x can be zero or a number positive.

**Examples:**

**Example1:**

**Input:**

given number =2048

**Output:**

The given numb 2048 is power of 2

**Example2:**

**Input:**

given number =256

**Output:**

The given numb 256 is power of 2

**Example3:**

**Input:**

given number =678

**Output:**

The given numb 678 is not power of 2

## Program to Find Whether a Number is a Power of Two in Python

There are several ways to check whether the given number is a power of 2 or not some of them are:

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### Method #1:Using log function

- This answer is just a mathematical one.
- If the log2(n) of the given number n is integer than it is power of 2
- Else it is not power of 2.

**Below is the implementation:**

# importing log from math from math import log # given number numb = 2048 # given base (here it is 2 as we have to check whether it is power of 2 or not) bas = 2 # calculating log2 of the given numb using log function logvalue = log(numb, bas) # if the value is integer then it is power of 2 if (int(logvalue) == logvalue): print("The given numb", numb, "is power of 2") # else it is not power of 2 else: print("The given numb", numb, "is not power of 2")

**Output:**

The given numb 2048 is power of 2

### Method #2:Using while loop

Continue dividing the number into two, i.e. do n = n/2 as long as n is 1 If n percent 2 is non-zero and n is not 1 in all iteration, then n is not 2. It is a power of 2, if n becomes 1.

**Below is the implementation:**

# function which returns true if the given number is power of 2 else it reeturns false def checktwoPower(numb): # checking if the number is 0 if (numb == 0): # if the number is 0 then it is not power of 2 hence return false return False # using while loop to iterate till the number not equal to 1 while (numb != 1): # if the bit is set bit then it is not power of 2 so return False if (numb % 2 != 0): return False # dividing n numb = numb // 2 return True # given number numb = 2048 # passing the given number to checktwoPower function # if the value is integer then it is power of 2 if (checktwoPower(numb)): print("The given numb", numb, "is power of 2") # else it is not power of 2 else: print("The given numb", numb, "is not power of 2")

**Output:**

The given numb 2048 is power of 2

### Method #3:Using Bitwise Operators

If the number is 2 power, the binary representationÂ of only 1 bit is set.

If we remove 1 from a power number 2, then all the bits are set and the set bit is unset after the set bits (just one bits are set according to point-1)

Therefore, if a number is 2, then

numb&(numb-1) == 0

Only if N is zero is the exception to the foregoing rule. As a power of two, it will give zero which in fact is not. Therefore, we can explicitly see this in the check.

**Below is the implementation:**

# function which returns true if the given number is power of 2 else it reeturns false def checktwoPower(numb): return numb and (not(numb & (numb-1))) # given number numb = 2048 # passing the given number to checktwoPower function # if the value is integer then it is power of 2 if (checktwoPower(numb)): print("The given numb", numb, "is power of 2") # else it is not power of 2 else: print("The given numb", numb, "is not power of 2")

**Output:**

The given numb 2048 is power of 2

### Method #4:By Calculating total number of set bits

A simple method is to take each bit into consideration in a number (set or unset) and hold a counter to track the set bits if the total number of set bits is 1 then the number is power of 2 else it is not the power of 2

**Approach:**

- Set the variable to say count to 0 to count the total number of set bits.
- We utilize the while loop.
- Weâ€™ll keep going till the number is bigger than zero (Condition of while statement)
- Using the & operator, we will determine whether the last check bit is set or not.
- If the check bit is 1, it indicates that the bit is set, and we increment the count.
- Divide the given number by 2.
- If the count is 1 then it is the power of 2 hence return true
- Else return false

We useÂ **n&1** to check whether it is set bit or not.

**Below is the implementation:**

# function which returns true if the given number is power of 2 else it reeturns false def checktwoPower(numb): # checking if the given number is greater than 1 if numb > 1: # Set the variable say setbitcount to 0 to count the total number of set bits. setbitcount = 0 # looping till number greater than 0 using while loop while(numb > 0): # We will get the last check bit whether it is set bit or not using & operator # checking if the check bit is 1 or not # if the check bit is 1 then increment the setbitcount if(numb & 1): setbitcount = setbitcount+1 # divide the number by 2 numb = numb//2 # checking if the total number of setbits are 1 or not return (setbitcount == 1) # given number numb = 2048 # passing the given number to checktwoPower function # if the value is integer then it is power of 2 if (checktwoPower(numb)): print("The given numb", numb, "is power of 2") # else it is not power of 2 else: print("The given numb", numb, "is not power of 2")

**Output:**

The given numb 2048 is power of 2

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