To use a subtraction calculator, follow these steps:

1. Open a web browser and go to a search engine such as Google.
2. Type “subtraction calculator” in the search bar and hit enter.
3. You will see a list of results with various online subtraction calculators. Choose one that suits your needs.
4. Once you have opened the calculator, you will see two boxes for entering the values to be subtracted.
5. Enter the first number in the box labeled “Minuend” or “First number”.
6. Enter the second number in the box labeled “Subtrahend” or “Second number”.
7. Click on the “Calculate” button.
8. The result of the subtraction will be displayed in the box labeled “Difference” or “Result”.

Alternatively, if you are using a physical calculator:

1. Turn on the calculator.
2. Enter the first number.
3. Press the subtraction button (usually represented by “-“).
4. Enter the second number.
5. Press the equals button (usually represented by “=” or “Enter”).
6. The result of the subtraction will be displayed on the calculator screen.