Corbettmaths method: A systematic approach to adding decimals that emphasizes aligning decimal points, using placeholders, and performing column addition with carrying.
- Write the numbers vertically with decimal points aligned
- Add zeros as placeholders if needed to match decimal places
- Perform the addition column by column from right to left
- Carry over when the sum in a column is 10 or more
- Bring the decimal point straight down in the answer
+ 8.35
------
32.95
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 = 5
Tenths: 6 + 3 = 9
Ones: 4 + 8 = 12 (write 2, carry 1)
Tens: 2 + 0 + 1 = 3
24.6 + 8.35 = 32.95
• Decimal Alignment Rule: All decimal points must be in the same vertical column
• Placeholder Rule: Add zeros to match decimal places when needed
• Column Addition Rule: Add digits in the same place value columns
• Carrying Rule: When sum ≥ 10, write the units digit and carry the tens digit
Corbettmaths method: A systematic approach to adding decimals that emphasizes aligning decimal points, using placeholders, and performing column addition with carrying.
+ 8.400
+ 3.096
------
27.216
Write all three numbers vertically with decimal points in the same column.
15.72 becomes 15.720 and 8.4 becomes 8.400 to match the three decimal places in 3.096.
Thousandths: 0 + 0 + 6 = 6
Hundredths: 2 + 0 + 9 = 11 (write 1, carry 1)
Tenths: 7 + 4 + 0 + 1 = 12 (write 2, carry 1)
Ones: 5 + 8 + 3 + 1 = 17 (write 7, carry 1)
Tens: 1 + 0 + 0 + 1 = 2
15.72 + 8.4 + 3.096 = 27.216
• Decimal Alignment Rule: All decimal points must be in the same vertical column
• Placeholder Rule: Add zeros to match decimal places when needed
• Column Addition Rule: Add digits in the same place value columns
• Carrying Rule: When sum ≥ 10, write the units digit and carry the tens digit
Corbettmaths method: A systematic approach to adding decimals that emphasizes aligning decimal points, using placeholders, and performing column addition with carrying.
12.500
+ 9.007
------
29.347
Write all three numbers vertically with decimal points in the same column.
7.84 becomes 7.840 and 12.5 becomes 12.500 to match the three decimal places in 9.007.
Thousandths: 0 + 0 + 7 = 7
Hundredths: 4 + 0 + 0 = 4
Tenths: 8 + 5 + 0 = 13 (write 3, carry 1)
Ones: 7 + 2 + 9 + 1 = 19 (write 9, carry 1)
Tens: 0 + 1 + 0 + 1 = 2
7.84 + 12.5 + 9.007 = 29.347
• Decimal Alignment Rule: All decimal points must be in the same vertical column
• Placeholder Rule: Add zeros to match decimal places when needed
• Column Addition Rule: Add digits in the same place value columns
• Carrying Rule: When sum ≥ 10, write the units digit and carry the tens digit
Definitions:
Corbettmaths Method: A systematic approach to adding decimals that emphasizes aligning decimal points, using placeholders, and performing column addition with carrying.
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.
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
• Carry over when the sum in a column is 10 or more
• 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 addition column by column from right to left
4. Carry over when the sum in a column is 10 or more
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 = 32.95 ✓
Multiple: 15.72 + 8.4 + 3.096 → 15.720 + 8.400 + 3.096 = 27.216 ✓
With carrying: 7.84 + 12.5 + 9.007 → 7.840 + 12.500 + 9.007 = 29.347 ✓
Tips and Tricks:
• Always align decimal points first before adding
• 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 carry when the sum in a column is 10 or more
• 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
= Decimal Point 3
= Answer Decimal Point
Corbettmaths Method: A systematic approach to adding decimals that emphasizes aligning decimal points, using placeholders, and performing column addition with carrying
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
- Align vertically: Write numbers with decimal points in the same column
- Add placeholders: Add zeros to match decimal places if needed
- Perform addition: Work column by column from right to left
- Carry when needed: When sum ≥ 10, carry to the 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
• Carry over: When sum ≥ 10, carry to the next column
• Bring down decimal: The decimal point in the answer aligns with the others
Corbettmaths method: A systematic approach to adding decimals that emphasizes aligning decimal points, using placeholders, and performing column addition with carrying.
+ 7.200
+ 14.368
------
39.618
Write all three numbers vertically with decimal points in the same column.
18.05 becomes 18.050 and 7.2 becomes 7.200 to match the three decimal places in 14.368.
Thousandths: 0 + 0 + 8 = 8
Hundredths: 5 + 0 + 6 = 11 (write 1, carry 1)
Tenths: 0 + 2 + 3 + 1 = 6
Ones: 8 + 7 + 4 = 19 (write 9, carry 1)
Tens: 1 + 0 + 1 + 1 = 3
18.05 + 7.2 + 14.368 = 39.618
• Decimal Alignment Rule: All decimal points must be in the same vertical column
• Placeholder Rule: Add zeros to match decimal places when needed
• Column Addition Rule: Add digits in the same place value columns
• Carrying Rule: When sum ≥ 10, write the units digit and carry the tens digit
Corbettmaths method: A systematic approach to adding decimals that emphasizes aligning decimal points, using placeholders, and performing column addition with carrying.
+ 9.430
+ 6.005
+ 3.721
------
44.956
Write all four numbers vertically with decimal points in the same column.
25.8 becomes 25.800, 9.43 becomes 9.430, and 3.721 remains as is to match the three decimal places.
Thousandths: 0 + 0 + 5 + 1 = 6
Hundredths: 0 + 3 + 0 + 2 = 5
Tenths: 8 + 4 + 0 + 7 = 19 (write 9, carry 1)
Ones: 5 + 9 + 6 + 3 + 1 = 24 (write 4, carry 2)
Tens: 2 + 0 + 0 + 0 + 2 = 4
25.8 + 9.43 + 6.005 + 3.721 = 44.956
• Decimal Alignment Rule: All decimal points must be in the same vertical column
• Placeholder Rule: Add zeros to match decimal places when needed
• Column Addition Rule: Add digits in the same place value columns
• Carrying Rule: When sum ≥ 10, write the units digit and carry the tens digit