Master adding and subtracting decimals with proper decimal point alignment. Learn decimal operations through shopping scenarios and real-world applications.
Scenario: You're shopping for school supplies! You want to buy a pencil for $0.85 and an eraser for $1.20. How much will you pay in total? Later, you have $5.00 and spend $2.75. How much change will you get back?
This is where decimal addition and subtraction skills come in handy! The key is to align the decimal points so that you're adding or subtracting the same place values.
Always align decimal points vertically when adding or subtracting decimals. This ensures you're working with the same place values.
0.85
+1.20
-----
2.05
When decimals have different numbers of decimal places, add zeros to make them the same length.
3.5 becomes 3.50
when adding to 2.75
Write the numbers vertically with decimal points directly under each other. Add zeros if needed to make all numbers have the same number of decimal places.
Example: 0.85 + 1.20 → Write 0.85 over 1.20 with decimal points aligned
Work from right to left, adding or subtracting each place value. Carry over when adding, borrow when subtracting.
Example: 0.85 + 1.20 = 2.05 (5 hundredths + 0 hundredths = 5 hundredths)
The decimal point in your answer should be directly below the decimal points in the numbers you're adding or subtracting.
Example: 5.00 - 2.75 = 2.25 (decimal point stays in the same column)
Calculate shopping totals:
Practice decimal operations:
1. 2.5 + 1.3 = ?
2. 4.75 + 2.25 = ?
3. 6.8 + 3.45 = ?
4. 9.2 + 1.75 = ?
5. 5.7 - 2.3 = ?
6. 8.45 - 3.25 = ?
7. 12.6 - 4.8 = ?
8. 15.75 - 7.25 = ?
9. 3.5 + 2.75 - 1.25 = ?
10. 7.8 - 2.45 + 1.2 = ?
11. 12.5 - 4.75 + 2.25 = ?
12. 8.9 + 3.15 - 2.05 = ?
Wrong: 2.5 + 1.23 = 3.73 (misaligned)
Correct: 2.50 + 1.23 = 3.73 (aligned)
Wrong: 5.2 - 3.75 = 2.53 (can't subtract 5 from 2)
Correct: 5.20 - 3.75 = 1.45 (borrow from 5 to make 12)
Always align decimal points when adding or subtracting
Add zeros to make all numbers have the same number of decimal places
Work from right to left, carrying over when adding and borrowing when subtracting
The decimal point in your answer goes directly below the other decimal points