- Enter your subtraction in the first input field.
- Use the algorithm on a piece of paper to subtract the numbers.
- Enter your answer in the second input field.
- Click "CHECK" to see if you did it right.

- Enter your subtraction in the first input field.
- Use the algorithm on a piece of paper to subtract the numbers.
- Enter your answer in the second input field.
- Click "CHECK" to see if you did it right.

(click an example...)