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Y.2 Learn to subtract decimal numbers

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What does it mean to subtract decimals?

Subtracting decimals means finding the difference between two numbers that have digits to the right of a decimal point. Each place value must line up correctly before subtracting.

Example:
  • 6.4 − 2.3 = 4.1
Note

The decimal point separates whole numbers from parts of a whole. Always keep the decimal points in the same column when you subtract.

How to line up decimals before subtracting

Before subtracting, write the numbers so their decimal points are directly under each other. This helps line up ones, tenths, hundredths, and other place values correctly.

Example:
  • Write 5.67 and 3.45 as:
          5.67
        − 3.45
          ----
          2.22
                  
Note

Each column represents a place value. Subtract digits in the same place value column just like you do with whole numbers.

What if the decimals have different lengths?

If one number has fewer digits after the decimal point, you can add zeros to make the lengths equal. This helps you subtract more easily without changing the number’s value.

Example:
  • 4.5 − 2.36 = ?
    Rewrite 4.5 as 4.50:
          4.50
        − 2.36
          ----
          2.14
                  
Note

Adding zeros after a decimal does not change a number’s value. It only makes subtraction clearer and easier to line up.

Borrowing when subtracting decimals

Sometimes you cannot subtract because the top digit is smaller than the bottom digit in a column. In that case, borrow from the next place value to the left, just like with whole numbers.

Example:
  • 7.2 − 3.85 = ?
    Rewrite 7.2 as 7.20, then subtract:
          7.20
        − 3.85
          ----
          3.35
                  
Note

Always start subtracting from the rightmost digit (the smallest place value). Borrow from the next place when needed to keep subtraction accurate.

Check your answer

You can check your subtraction by adding the difference to the smaller number. The sum should equal the larger number.

Example:
  • 6.8 − 4.25 = 2.55
    Check: 4.25 + 2.55 = 6.80 ✓
Note

If the sum matches the original larger number, your subtraction is correct. Always double-check to catch small errors in borrowing or lining up decimals.