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Kavitha
Kavitha

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Looping Programs JS(Part 2)

18. Addition of first n numbers
Program:

<!DOCTYPE html>
<html>
<head>
    <title>document</title>
</head>
<body>
    <script>
        let n=50;
        let sum=0;
        for(let i=1;i<=n;i++){
            sum+=i;
        }
        document.write("Sum: "+sum);
    </script>
</body>
</html>
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19.Factorial
Program:

<!DOCTYPE html>
<html>
<head>
    <title>document</title>
</head>
<body>
    <script>
        let n=5;
        let fact=1;
        for(let i=1;i<=n;i++){
            fact=fact*i;
        }
        document.write(fact);
    </script>
</body>
</html>
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20.Greatest Common Divisor
Program:

<!DOCTYPE html>
<html>
<head>
    <title>document</title>
</head>
<body>
    <script>
        let n1=2;
        let n2=4;
        while(n2!==0){
            let temp=n2;
            n2=n1%n2;
            n1=temp;
        }
        document.write("GCD:"+n1);

    </script>
</body>
</html>
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21.Least Common Multiple
Program:

<!DOCTYPE html>
<html>
<head>
    <title>document</title>
</head>
<body>
    <script>
        let n1 = 2;
        let n2 = 4;

        let a = n1;
        let b = n2;

        while (n2 !== 0) {
            let temp = n2;
            n2 = n1 % n2;
            n1 = temp;
        }

        let gcd = n1;

        let lcm = (a * b) / gcd;

        document.write("LCM = " + lcm);
    </script>
</body>
</html>
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22. 2^5

console.log(Math.pow(2, 5)); // Output: 32
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23. Decimal to Binary

let decimal = 23;
let binary = decimal.toString(2);
console.log(binary); // Output: 10111
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24. Binary to Decimal

let binaryNum = "10111";
let decimalNum = parseInt(binaryNum, 2);
console.log(decimalNum); // Output: 23
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25. Fibonacci Series

let n = 10;
let a = 0, b = 1;
console.log(a);
console.log(b);
for (let i = 2; i < n; i++) {
    let c = a + b;
    console.log(c);
    a = b;
    b = c;
}
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26. Swapping Two Numbers

let x = 5, y = 10;
let temp = x;
x = y;
y = temp;
console.log(x, y); // Output: 10 5
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27. Swapping Without Third Variable

let a = 5, b = 10;
a = a + b;
b = a - b;
a = a - b;
console.log(a, b); // Output: 10 5
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28. Fibonacci Without Third Variable

let n1 = 0, n2 = 1;
console.log(n1);
console.log(n2);
for (let i = 2; i < 10; i++) {
    n2 = n1 + n2;
    n1 = n2 - n1;
    console.log(n2);
}
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29. Odd Positions & Even Positions

let arr = [1,2,3,4,5,6,7,8,9,10];
let odd = [], even = [];
for (let i = 0; i < arr.length; i++) {
    if (i % 2 === 0) even.push(arr[i]);
    else odd.push(arr[i]);
}
console.log("Even Positions:", even);
console.log("Odd Positions:", odd);
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30. First 10 Prime Numbers

let primes = [];
for (let i = 2; primes.length < 10; i++) {
    let isPrime = true;
    for (let j = 2; j <= Math.sqrt(i); j++) {
        if (i % j === 0) isPrime = false;
    }
    if (isPrime) primes.push(i);
}
console.log(primes);
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31. Sum of Digits Until Single Digit

let num = 9876;
while (num > 9) {
    let sum = 0;
    num.toString().split('').forEach(d => sum += Number(d));
    num = sum;
}
console.log(num);
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32. Printing 5! 4! 3! 2! 1!

function factorial(n) {
    return n <= 1 ? 1 : n * factorial(n-1);
}
for (let i = 5; i >= 1; i--) {
    console.log(factorial(i));
}
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33. Printing 1*10 2*9 3*8 4*7

for (let i = 1, j = 10; i <= 4; i++, j--) {
    console.log(i * j);
}
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34. Printing 1 11 121

for (let i = 0; i < 3; i++) {
    console.log(Math.pow(11, i));
}
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35. Printing 1 8 27 64

for (let i = 1; i <= 4; i++) {
    console.log(Math.pow(i, 3));
}
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36. Printing 1 4 9 16 … 100

for (let i = 1; i <= 10; i++) {
    console.log(i * i);
}
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37. Printing 1 4 27 256

let powers = [1,2,3,4];
for (let i = 0; i < powers.length; i++) {
    console.log(Math.pow(powers[i], powers[i]));
}
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38. Square Root of a Number

let nSqrt = 64;
console.log(Math.sqrt(nSqrt)); // Output: 8
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39. Spy Number

A Spy number is one where sum of digits = product of digits.

let spyNum = 1124;
let sum = 0, product = 1;
spyNum.toString().split('').forEach(d => {
    let num = Number(d);
    sum += num;
    product *= num;
});
console.log(sum === product ? "Spy Number" : "Not Spy Number");
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40. Prime Numbers in Fibonacci Series

let fib = [0,1];
for (let i = 2; i < 10; i++) {
    fib[i] = fib[i-1] + fib[i-2];
}
let primesInFib = fib.filter(n => {
    if (n < 2) return false;
    for (let i = 2; i <= Math.sqrt(n); i++) {
        if (n % i === 0) return false;
    }
    return true;
});
console.log(primesInFib);
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