Here are some simple JavaScript programs that demonstrate **variables, data types, and operators**:

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## 1. Basic Variables and Data Types

```javascript
// Variables
let name = "John";      // String
let age = 25;           // Number
let isStudent = true;   // Boolean

console.log("Name:", name);
console.log("Age:", age);
console.log("Is Student:", isStudent);
```

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## 2. Using Arithmetic Operators

```javascript
let a = 10;
let b = 5;

let sum = a + b;
let difference = a - b;
let product = a * b;
let quotient = a / b;
let remainder = a % b;

console.log("Sum:", sum);
console.log("Difference:", difference);
console.log("Product:", product);
console.log("Quotient:", quotient);
console.log("Remainder:", remainder);
```

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## 3. Assignment Operators

```javascript
let x = 10;

x += 5;  // x = x + 5
x -= 2;  // x = x - 2
x *= 3;  // x = x * 3

console.log("Final value of x:", x);
```

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## 4. Comparison Operators

```javascript
let num1 = 10;
let num2 = 20;

console.log(num1 == num2);   // false
console.log(num1 != num2);   // true
console.log(num1 > num2);    // false
console.log(num1 < num2);    // true
```

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## 5. Logical Operators

```javascript
let isAdult = true;
let hasID = false;

console.log(isAdult && hasID); // false
console.log(isAdult || hasID); // true
console.log(!isAdult);         // false
```

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## 6. Simple Calculator Program

```javascript
let num1 = 12;
let num2 = 4;

console.log("Addition:", num1 + num2);
console.log("Subtraction:", num1 - num2);
console.log("Multiplication:", num1 * num2);
console.log("Division:", num1 / num2);
```

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## 7. Area of a Circle (Using Variables & Operators)

```javascript
let radius = 7;
const pi = 3.14;

let area = pi * radius * radius;

console.log("Area of Circle:", area);
```

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If you want, I can also give **practice problems**, **real-world mini projects**, or **output-based questions** for exams 👍