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//function to find all prime numbers up to a given number and store them in an array
function findPrimes(upToNum) {
const primeNums = [2]; // Initialize with 2, as it's the only even prime
for (let i = 3; i <= upToNum; i++) {
let isPrime = true;
// Check if i is divisible by any prime number found so far
for (let j = 0; j < primeNums.length; j++) {
if (i % primeNums[j] === 0) {
isPrime = false;
break;
}
}
if (isPrime) {
primeNums.push(i);
}
}
return primeNums;
}
console.log(findPrimes(50));
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function isPrime(num) {
for (let i = 2; i * i <= num; i++)
if (num % i === 0)
return false;
return num > 1;
}
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function findPrime(to) {
let factor;
for (let n = 0; n < to; n++) {
factor = 0
for (let p = 0; p < to; p++)
if (n % p == 0) factor++;
if (factor == 2) console.log(n);
}
}
console.log(30) //2 3 5 7 11 13 17 19 23 29
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// To understand this let's understand that Prime number has only two factors
// 1) first factor = number it self
// 2) second factor = 1
// for instance 3 has only factors 3*1 = 3 and 1;
// I have taken two for loop to get two different numbers once we get two factors then it will console i
function getPrime(until) {
let factor;
for (let i = 0; i < n; i++) {
factor = 0;
for (let j = 1; j <= n; j++) {
if (i % j == 0) {
factor++;
}
}
if (factor == 2) console.log(i);
}
}
getPrime(30);
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const array = [-3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13];
function isPrime(num) {
for (let i = 2; num > i; i++) {
if (num % i === 0) {
return false;
}
}
return num > 1;
}
console.log(array.filter(isPrime)); // [2, 3, 5, 7, 11, 13]
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// 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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// This program will use a loop to check if a number is prime.
// To start, set a flag to true
let isPrime = true;
// We will use a for loop to loop through numbers from 2 to the number we are testing
// We can start at 2 because all numbers are divisible by 1
const numToTest = 17;
for(let i = 2; i < numToTest; i++) {
// If the number is divisible by any other number (besides 1 and itself)
// then it is not a prime number
if(numToTest % i === 0) {
isPrime = false;
break;
}
}
// Finally, output the result
if(numToTest == 1) { console.log(`${numToTest} is not a prime number`);}
else if (isPrime) {
console.log(`${numToTest} is a prime number`);
} else {
console.log(`${numToTest} is not a prime number`); }
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function showPrimes(n) {
for (let i = 2; i < n; i++) {
if (!isPrime(i)) continue;
console.log(i);
}
}
function isPrime(n) {
for (let i = 2; i < n; i++) {
if (n % i == 0) return false;
}
return true;
}
showPrimes(10)
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function isPrime(number) {
for (let i = 2; i * i <= number; i++)
if (number % i === 0)
return false;
return number > 1;
}