JavaScript: Power of three

JavaScript Math: Exercise-107 with Solution

Check Power of Three

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

In mathematics, a power of three is a number of the form 3ⁿ where n is an integer – that is, the result of exponentiation with number three as the base and integer n as the exponent.

Test Data:
(27) -> true
(9) -> true
(36) -> false

Sample Solution:

Solution-1

JavaScript Code:

/**
 * Function to check if a number is a power of three.
 * @param {number} n - The number to be checked.
 * @returns {boolean} - True if the number is a power of three, false otherwise.
 */
function test(n) {
    // Check if the logarithm of the number to the base 3 is an integer
    return (Math.log10(n) / Math.log10(3)) % 1 == 0;
}

// Test cases
n = 27;
console.log("Number n = " + n);
console.log("Check if the said number is a power of three: " + test(n));
n = 9;
console.log("Number n = " + n);
console.log("Check if the said number is a power of three: " + test(n));
n = 36;
console.log("Number n = " + n);
console.log("Check if the said number is a power of three: " + test(n));

Output:

Number n = 27
Check the said number is power of three or not? true
Number n = 9
Check the said number is power of three or not? true
Number n = 36
Check the said number is power of three or not? false

Flowchart:

Live Demo:

See the Pen javascript-math-exercise-107 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 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 if the said number is a power of four: true
Number n = 4096
Check if the said number is a power of four: true
Number n = 36
Check if the said number is a power of four: false

Flowchart:

Live Demo:

See the Pen javascript-math-exercise-107-1 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript function that checks whether a number is a power of three by repeatedly dividing by 3.
• Write a JavaScript function that uses logarithms to determine if the base-3 logarithm of a number is an integer.
• Write a JavaScript function that recursively divides a number by three and checks if it eventually equals one.
• Write a JavaScript function that validates the input and properly handles edge cases when checking for a power of three.

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