Add and subtract decimals
key notes:
🧩 Line Up the Decimal Points!
When adding or subtracting decimals, always line up the decimal points.
➡️ This keeps the place values (tenths, hundredths, thousandths) correct.
Example:
3.45
+ 2.30
------
🟡 Decimal alignment = no mistakes!
🔢 Add Zeroes if Needed
If a number has fewer digits, add trailing zeroes to make calculation easier.
Example:
3.4 → 3.40
⭐ Helps keep tenths & hundredths aligned.
➕ Add Like Whole Numbers
Once decimals are lined up, ignore the decimal and add normally.
Then place the decimal point in the answer directly under the others.
🧮✨
➖ Subtraction Works the Same
Line up decimals → Add zeroes → Subtract like whole numbers → Place decimal.
Example:
5.60
- 3.75
------
🟥 Borrowing may be needed!
🧠 Understand Place Values
Each digit has a value:
- Tenths (0.1)
- Hundredths (0.01)
- Thousandths (0.001)
🎯 This helps avoid confusion during addition/subtraction.
🔍 Check Your Answer for Reasonableness
Estimate before solving!
Example:
3.75 + 2.60 ≈ 4 + 3 = 7
✔ Helps catch mistakes.
🚫 Do NOT Move Decimal Points
❌ Never shift decimal points when adding/subtracting.
✔ Only line them up.
💡 Word Problems Use Real-Life Context
Decimals appear in:
🍎 Money
📏 Measurements
⛽ Fuel
🏃 Distances
Understanding decimals helps in everyday life!
🎉 Practice Makes You a Decimal Master!
The more you practice, the faster and more accurate you get!
⭐💪🔢
Learn with an example
🔔 Add.
0.6 + 0.6 = ___ . ___
Remember to line up the decimal points.
0.6 + 0.6 = ?
Add as you would add whole numbers. Remember to write the decimal point in the answer.
0.6 + 0.6 = 1.2
The sum is 1.2.
🔔 Add.
6.71 + 5.47 = ___ . ___
Remember to line up the decimal points.
6.71 + 5.47 = ?
Add as you would add whole numbers. Remember to write the decimal point in the answer.
The sum is 12.18.
Add.
- 1.6
- 1.4
- 1.3
- 2
Remember to line up the decimal points.
Add as you would add whole numbers. Remember to write the decimal point in the answer.
The sum is 1.6.
Let’s practice!
