Long subtraction is a method for subtracting multi-digit numbers.

1. Stack Numbers: Write the smaller number below the larger number, aligning the digits in columns.
2. Start from the Right: Begin with the rightmost column.
3. Subtract Digits: Subtract the bottom digit from the top digit. If the top digit is smaller, you must "borrow" from the column to the left.
4. Borrowing: To borrow, reduce the digit in the column to the left by 1, and add 10 to the current top digit. Then subtract.
5. Continue Left: Repeat the process for each column, moving from right to left.

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