Features:

1. Input: The user enters an amount and selects the VAT rate (e.g., 20% for standard rate, 5% for reduced rate, or 0% for zero rate).
2. Two Options:
   • Add VAT: Adds VAT to the entered amount.
   • Remove VAT: Removes VAT from the entered amount.
3. Output: Displays the VAT amount and the total amount including or excluding VAT.

How It Works:

• Add VAT: The calculator multiplies the entered amount by the VAT percentage and adds it to the original amount.
• Remove VAT: The calculator removes the VAT from the total to show the VAT-exclusive amount.