JavaScript: Power of four

JavaScript Math: Exercise-108 with Solution

Write a JavaScript program to check whether a given integer is a power of four or not.

In arithmetic and algebra, the fourth power of a number n is the result of multiplying four instances of n together. So: n⁴ = n × n × n × n
Fourth powers are also formed by multiplying a number by its cube. Furthermore, they are squares of squares.
The sequence of fourth powers of integers (also known as biquadrates or tesseractic numbers) is:
0, 1, 16, 81, 256, 625, 1296, 2401, 4096, 6561, 10000, 14641, 20736, 28561, 38416, 50625, 65536, 83521, 104976, 130321, 160000, 194481, 234256, 279841, 331776, 390625, 456976, 531441, 614656, 707281, 810000, ...

Test Data:
(16) -> true
(4096) -> true
(36) -> false

Sample Solution:

Solution-1

JavaScript Code:

/**
 * Function to check if a number is a power of four.
 * @param {number} n - The number to be checked.
 * @returns {boolean} - True if the number is a power of four, false otherwise.
 */
function test(n) {
  // Check if the number is less than 1
  if (n < 1) {
    return false;
  }

  // Divide the number by 4 until it is not divisible by 4
  while (n % 4 === 0) {
    n = n / 4;
  }
  
  // Check if the resulting number is 1
  return n === 1;
}

// Test cases
n = 16;
console.log("Number n = " + n);
console.log("Check if the said number is a power of four: " + test(n));
n = 4096;
console.log("Number n = " + n);
console.log("Check if the said number is a power of four: " + test(n));
n = 36;
console.log("Number n = " + n);
console.log("Check if the said number is a power of four: " + test(n));

Output:

Number n = 16
Check the said number is power of four or not? true
Number n = 4096
Check the said number is power of four or not? true
Number n = 36
Check the said number is power of four or not? false

Flowchart:

Live Demo:

See the Pen javascript-math-exercise-108 by w3resource (@w3resource) on CodePen.

Solution-2

JavaScript Code:

/**
 * Function to check if a number is a power of four.
 * @param {number} n - The number to be checked.
 * @returns {boolean} - True if the number is a power of four, false otherwise.
 */
function test(n) {
    // Check if the number is 1 or 4
	if(n === 1 || n === 4) return true;
    // Check if the number is less than 4
	if(n < 4) return false;
    // Recursively call the function with n divided by 4
	return test(n / 4);
}

// Test cases
n = 16;
console.log("Number n = " + n);
console.log("Check if the said number is a power of four: " + test(n));
n = 4096;
console.log("Number n = " + n);
console.log("Check if the said number is a power of four: " + test(n));
n = 36;
console.log("Number n = " + n);
console.log("Check if the said number is a power of four: " + test(n));

Output:

Number n = 16
Check the said number is power of four or not? true
Number n = 4096
Check the said number is power of four or not? true
Number n = 36
Check the said number is power of four or not? false

Flowchart:

Live Demo:

See the Pen javascript-math-exercise-108-1 by w3resource (@w3resource) on CodePen.

Improve this sample solution and post your code through Disqus.

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