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JavaScript: Power of three

JavaScript Math: Exercise-107 with Solution

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:

HTML Code:

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>JavaScript program to Power of three or not</title>
</head>
<body>

</body>
</html>

Solution-1

JavaScript Code:

function test(n) {
 return (Math.log10(n) / Math.log10(3)) % 1 == 0;
}

n = 27
console.log("Number n = " +n)
console.log("Check the said number is power of three or not? "+test(n));
n = 9
console.log("Number n = " +n)
console.log("Check the said number is power of three or not? "+test(n));
n = 36
console.log("Number n = " +n)
console.log("Check the said number is power of three or not? "+test(n));

Sample 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:

JavaScript: Power of three.

Live Demo:

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


Solution-2

JavaScript Code:

function test(n) {
 if (n < 1) {
    return false;
  }
  while (n % 3 === 0) {
    n = n / 3;
  }
  return n === 1;
}
n = 27
console.log("Number n = " +n)
console.log("Check the said number is power of three or not? "+test(n));
n = 9
console.log("Number n = " +n)
console.log("Check the said number is power of three or not? "+test(n));
n = 36
console.log("Number n = " +n)
console.log("Check the said number is power of three or not? "+test(n));

Sample 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:

JavaScript: Power of three.

Live Demo:

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


Improve this sample solution and post your code through Disqus

Previous: Least number of perfect square that sums upto n.
Next: Power of four.

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JavaScript: Tips of the Day

Shorten an array using its length property

A great way of shortening an array is by redefining its length property.

let array = [0, 1, 2, 3, 4, 5, 6, 6, 8, 9]
array.length = 4
// Result: [0, 1, 2, 3]

Important to know though is that this is a destructive way of changing the array. This means you lose all the other values that used to be in the array.

Ref: https://bit.ly/2LBj213