Algorithm
- Input: Accept a positive integer as input.
- Edge Cases: Check if the input is less than 2. If yes, it's not a prime number.
- Loop: Iterate from 2 to the square root of the input number (rounded up to the nearest integer).
- If the input number is divisible evenly by any number in this range, it's not a prime number.
- Output: If the loop completes without finding a divisor, the number is a prime number.
Code Examples
#1 Code Example- Check Prime Number
Code -
Javascript Programming
// program to check if a number is prime or not
// take input from the user
const number = parseInt(prompt("Enter a positive number: "));
let isPrime = true;
// check if number is equal to 1
if (number === 1) {
console.log("1 is neither prime nor composite number.");
}
// check if number is greater than 1
else if (number > 1) {
// looping through 2 to number-1
for (let i = 2; i < number; i++) {
if (number % i == 0) {
isPrime = false;
break;
}
}
if (isPrime) {
console.log(`${number} is a prime number`);
} else {
console.log(`${number} is a not prime number`);
}
}
// check if number is less than 1
else {
console.log("The number is not a prime number.");
}
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Output
Enter a positive number: 23
23 is a prime number.
23 is a prime number.
Demonstration
JavaScript Programing Example to Check Prime Number-DevsEnv