Basic Calculator

A basic calculator built using HTML, CSS, JavaScript, and Bootstrap.
This project focuses on clean UI, accurate arithmetic operations, accessibility, and responsive design.

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Features

• Basic arithmetic operations
  • Addition (+)
  • Subtraction (−)
  • Multiplication (×)
  • Division (÷)
• Two-way display
  • Top: input expression
  • Bottom: calculated result
• Premium dark UI
  • Subtle gradients
  • Depth and button feedback
• Keyboard support
  • Numbers, operators, Enter, Backspace, Escape
• Accessible
  • ARIA roles and live regions
  • Screen-reader friendly output
• Responsive design
  • Built using Bootstrap grid and utilities

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Technology Stack

• HTML5 – semantic structure
• CSS3 – custom styling and premium UI effects
• JavaScript (Vanilla) – calculator logic and keyboard handling
• Bootstrap 5 – responsive layout and UI consistency

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How It Works

• The calculator displays user input and results on separate display lines for clarity.
• Multiplication and division are shown as × and ÷ in the UI, while internally handled safely using JavaScript operators.
• User interactions work seamlessly via both mouse clicks and keyboard input.
• Input validation prevents invalid expressions and handles errors gracefully.

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How to Run

1. Download or clone the repository
2. Open index.html in any modern web browser
   (No build tools or server required)

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Design Decisions

• No external calculation libraries to keep logic simple and transparent.
• Bootstrap only for layout, not for business logic.
• Two-way display improves readability compared to single-line calculators.
• Premium dark theme chosen for better contrast and modern appearance.

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Author

Developed as part of an internship task, with emphasis on:

• Clean code structure
• Usable UI/UX
• Accessibility and responsiveness

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License

This project is for educational and demonstration purposes.