Corbettmaths method: A systematic approach to subtracting decimals that emphasizes aligning decimal points, using placeholders, and performing column subtraction with borrowing.
- Write the numbers vertically with decimal points aligned
- Add zeros as placeholders if needed to match decimal places
- Perform the subtraction column by column from right to left
- Borrow when the top digit is smaller than the bottom digit
- Bring the decimal point straight down in the answer
- 8.35
------
16.25
Write 24.6 and 8.35 vertically with decimal points in the same column.
24.6 becomes 24.60 to match the two decimal places in 8.35.
Hundredths: 0 - 5 requires borrowing (10 - 5 = 5)
Tenths: 5 - 3 = 2 (after borrowing)
Ones: 4 - 8 requires borrowing (14 - 8 = 6)
Tens: 1 - 0 = 1 (after borrowing)
24.6 - 8.35 = 16.25
• Decimal Alignment Rule: All decimal points must be in the same vertical column
• Placeholder Rule: Add zeros to match decimal places when needed
• Column Subtraction Rule: Subtract digits in the same place value columns
• Borrowing Rule: When top digit < bottom digit, borrow from the next column
Corbettmaths method: A systematic approach to subtracting decimals that emphasizes aligning decimal points, using placeholders, and performing column subtraction with borrowing.
- 8.40
------
7.32
Write 15.72 and 8.4 vertically with decimal points in the same column.
8.4 becomes 8.40 to match the two decimal places in 15.72.
Hundredths: 2 - 0 = 2
Tenths: 7 - 4 = 3
Ones: 5 - 8 requires borrowing (15 - 8 = 7)
Tens: 0 - 0 = 0 (after borrowing)
15.72 - 8.4 = 7.32
• Decimal Alignment Rule: All decimal points must be in the same vertical column
• Placeholder Rule: Add zeros to match decimal places when needed
• Column Subtraction Rule: Subtract digits in the same place value columns
• Borrowing Rule: When top digit < bottom digit, borrow from the next column
Corbettmaths method: A systematic approach to subtracting decimals that emphasizes aligning decimal points, using placeholders, and performing column subtraction with borrowing.
- 17.846
------
5.204
Write 23.05 and 17.846 vertically with decimal points in the same column.
23.05 becomes 23.050 to match the three decimal places in 17.846.
Thousandths: 0 - 6 requires borrowing (10 - 6 = 4)
Hundredths: 4 - 4 = 0 (after borrowing)
Tenths: 9 - 8 = 1 (after borrowing)
Ones: 2 - 7 requires borrowing (12 - 7 = 5)
Tens: 1 - 1 = 0 (after borrowing)
23.05 - 17.846 = 5.204
• Decimal Alignment Rule: All decimal points must be in the same vertical column
• Placeholder Rule: Add zeros to match decimal places when needed
• Column Subtraction Rule: Subtract digits in the same place value columns
• Borrowing Rule: When top digit < bottom digit, borrow from the next column
Definitions:
Corbettmaths Method: A systematic approach to subtracting decimals that emphasizes aligning decimal points, using placeholders, and performing column subtraction with borrowing.
Decimal Point Alignment: Ensuring that all decimal points in a calculation are lined up vertically. This ensures that place values (tenths, hundredths, etc.) are properly matched.
Placeholder Zeros: Additional zeros added to decimal numbers to ensure all numbers have the same number of decimal places.
Borrowing: Taking 1 from the next higher place value when the top digit is smaller than the bottom digit in a column.
Core Rules:
• Always align decimal points in the same vertical column
• Add placeholder zeros when decimal places don't match
• Perform operations column by column according to place value
• Borrow when the top digit is smaller than the bottom digit
• Bring the decimal point straight down in the answer
Methods and Procedures:
1. Write the numbers vertically with decimal points aligned
2. Add placeholder zeros to match decimal places if needed
3. Perform the subtraction column by column from right to left
4. Borrow when the top digit is smaller than the bottom digit
5. Bring the decimal point straight down in the answer
6. Check that the decimal point in the answer aligns with the others
Examples:
Simple: 24.6 - 8.35 → 24.60 - 8.35 = 16.25 ✓
With borrowing: 15.72 - 8.4 → 15.72 - 8.40 = 7.32 ✓
More complex: 23.05 - 17.846 → 23.050 - 17.846 = 5.204 ✓
Tips and Tricks:
• Always align decimal points first before subtracting
• Add zeros as placeholders to make all numbers have the same number of decimal places
• Work from right to left, column by column
• Remember to borrow when the top digit is smaller than the bottom digit
• Use graph paper to help keep numbers aligned
Key Notes to Remember:
• Misaligned decimal points lead to incorrect answers
• Placeholder zeros don't change the value of the number
• The decimal point in the answer must align with the others
• Count decimal places in the answer - it should match the largest number of decimal places in the problem
= Decimal Point 2
= Answer Decimal Point
Corbettmaths Method: A systematic approach to subtracting decimals that emphasizes aligning decimal points, using placeholders, and performing column subtraction with borrowing
Decimal Point Alignment: Ensuring that all decimal points in a calculation are lined up vertically
Placeholder Zeros: Additional zeros added to decimal numbers to ensure all numbers have the same number of decimal places
Borrowing: Taking 1 from the next higher place value when the top digit is smaller than the bottom digit in a column
- Align vertically: Write numbers with decimal points in the same column
- Add placeholders: Add zeros to match decimal places if needed
- Perform subtraction: Work column by column from right to left
- Borrow when needed: When top digit < bottom digit, borrow from next column
- Bring down decimal: Put the decimal point in the answer directly below the others
- Verify alignment: Check that all decimal points align
• Align vertically: All decimal points must be in the same column
• Add placeholders: Use zeros to match decimal places when needed
• Column operations: Work with digits in the same place value columns
• Borrow when needed: When top digit < bottom digit, borrow from next column
• Bring down decimal: The decimal point in the answer aligns with the others
Corbettmaths method: A systematic approach to subtracting decimals that emphasizes aligning decimal points, using placeholders, and performing column subtraction with borrowing.
- 18.74
------
13.36
Write 32.1 and 18.74 vertically with decimal points in the same column.
32.1 becomes 32.10 to match the two decimal places in 18.74.
Hundredths: 0 - 4 requires borrowing (10 - 4 = 6)
Tenths: 0 - 7 requires borrowing (10 - 7 = 3)
Ones: 1 - 8 requires borrowing (11 - 8 = 3)
Tens: 2 - 1 = 1 (after borrowing)
32.1 - 18.74 = 13.36
• Decimal Alignment Rule: All decimal points must be in the same vertical column
• Placeholder Rule: Add zeros to match decimal places when needed
• Column Subtraction Rule: Subtract digits in the same place value columns
• Borrowing Rule: When top digit < bottom digit, borrow from the next column
Corbettmaths method: A systematic approach to subtracting decimals that emphasizes aligning decimal points, using placeholders, and performing column subtraction with borrowing.
- 28.670
------
16.333
Write 45.003 and 28.67 vertically with decimal points in the same column.
28.67 becomes 28.670 to match the three decimal places in 45.003.
Thousandths: 3 - 0 = 3
Hundredths: 0 - 7 requires borrowing (10 - 7 = 3)
Tenths: 9 - 6 = 3 (after borrowing)
Ones: 4 - 8 requires borrowing (14 - 8 = 6)
Tens: 3 - 2 = 1 (after borrowing)
45.003 - 28.67 = 16.333
• Decimal Alignment Rule: All decimal points must be in the same vertical column
• Placeholder Rule: Add zeros to match decimal places when needed
• Column Subtraction Rule: Subtract digits in the same place value columns
• Borrowing Rule: When top digit < bottom digit, borrow from the next column