## Q. PHP program to find whether a number is power of two or not.

Here you will find an algorithm and program in PHP to find whether the given number is power of 2 or not. Now first let us understand what power of two means.

**Explanation : **In mathematics, a power of two is a number of the form 2^n where n is an integer. Here we use a mathematical concept of Logarithm, The most simple method for finding whether a number is power of two or not is to simply take the log of the number on base 2 and if you get an integer then the number is the power of 2.

**For Example : ** 256, when we take log of 256 to the base 2 we get 8 which is integer, hence 256 is power of 2.

## Algorithm to find whether a number is power of two or not

START Step 1 → Take integer variable num Step 2 → find out the log number with base 2 Step 3 → if outcome is integer then DISPLAY number is power of 2. Step 4 → Otherwise, DISPLAY number is not power of 2. STOP

# PHP Program to Find Whether a Given Number is Power of 2

function Log2($x) { return (log10($x) / log10(2)); } function find_power_of_two($num) { return (ceil(Log2($num)) == floor(Log2($num))); } $num=256; if(find_power_of_two($num)) echo "$num is the power of two"; else echo "$num is not the power of two";

#### Output

256 is the power of two.