5. Basic Programs (Math & Logic)

1. Simple Arithmetic Calculator

Program 1: Basic Operations

				
					<script>
let a = 20, b = 5;
document.write(
  "Add: " + (a + b) + "<br>" +
  "Sub: " + (a - b) + "<br>" +
  "Mul: " + (a * b) + "<br>" +
  "Div: " + (a / b)
);
</script>

Program 2: User Input Calculator

				
					<script>
let x = Number(prompt("Enter first number"));
let y = Number(prompt("Enter second number"));
alert("Sum = " + (x + y));
</script>

2. Swap Two Numbers (With Temporary Variable)

Program 1: Basic Swap

				
					<script>
let a = 5, b = 10, temp;
temp = a;
a = b;
b = temp;
document.write(a + " " + b);
</script>

Program 2: User Input Swap

				
					<script>
let a = Number(prompt("Enter A"));
let b = Number(prompt("Enter B"));
let temp = a;
a = b;
b = temp;
alert("A = " + a + ", B = " + b);
</script>

3. Swap Two Numbers (Without Temporary Variable)

Program 1: Using Addition & Subtraction

				
					<script>
let a = 3, b = 7;
a = a + b;
b = a - b;
a = a - b;
document.write(a + " " + b);
</script>

Program 2: Using Array Destructuring

				
					<script>
let a = 4, b = 9;
[a, b] = [b, a];
document.write(a + " " + b);
</script>

4. Convert Celsius to Fahrenheit

Program 1: Fixed Value

				
					<script>
let c = 25;
let f = (c * 9/5) + 32;
document.write(f);
</script>

Program 2: User Input

				
					<script>
let c = Number(prompt("Enter Celsius"));
alert((c * 9/5) + 32);
</script>

5. Convert Fahrenheit to Celsius

Program 1: Fixed Value

				
					<script>
let f = 77;
let c = (f - 32) * 5/9;
document.write(c);
</script>

Program 2: User Input

				
					<script>
let f = Number(prompt("Enter Fahrenheit"));
alert((f - 32) * 5/9);
</script>

6. Find Square and Cube of a Number

Program 1: Using Operators

				
					<script>
let n = 4;
document.write("Square: " + (n*n) + "<br>Cube: " + (n*n*n));
</script>

Program 2: Using Math.pow()

				
					<script>
let n = 3;
document.write(Math.pow(n,2) + "<br>" + Math.pow(n,3));
</script>

7. Area of Circle

Program 1: Fixed Radius

				
					<script>
let r = 5;
document.write(Math.PI * r * r);
</script>
Program 2: User Input
<script>
let r = Number(prompt("Enter radius"));
alert(Math.PI * r * r);
</script>

8. Area of Rectangle

Program 1: Fixed Values

				
					<script>
let length = 10, width = 4;
document.write(length * width);
</script>

Program 2: User Input

				
					<script>
let l = Number(prompt("Enter length"));
let w = Number(prompt("Enter width"));
alert(l * w);
</script>

9. Area of Triangle

Program 1: Basic Formula

				
					<script>
let base = 8, height = 5;
document.write(0.5 * base * height);
</script>

Program 2: User Input

				
					<script>
let b = Number(prompt("Enter base"));
let h = Number(prompt("Enter height"));
alert(0.5 * b * h);
</script>

10. Check Even or Odd Number

Program 1: Simple Condition

				
					<script>
let n = 6;
if(n % 2 === 0)
  document.write("Even");
else
  document.write("Odd");
</script>

Program 2: Ternary Operator

				
					<script>
let n = Number(prompt("Enter a number"));
alert(n % 2 === 0 ? "Even" : "Odd");
</script>