Add and subtract decimals: word problems

key notes :

🔢 Understand the Problem

• Read the question carefully.
• Identify the numbers with decimals and the operation needed: addition ➕ or subtraction ➖.
• Example: “Ravi bought 2.5 kg apples and 1.75 kg bananas. How many kg fruits did he buy?”

📝 Line Up the Decimal Points

• Write numbers vertically.
• Align the decimal points before adding or subtracting.
• Example: 2.50 + 1.75 ---- 4.25

➕ Adding Decimals

• Add as usual, starting from the right (smallest place value).
• Bring the decimal point straight down in the answer.
• Check your answer makes sense in the context of the problem. ✅

➖ Subtracting Decimals

• Subtract as usual, starting from the right.
• Bring the decimal point straight down.
• If needed, borrow like in whole numbers.
• Example: 5.60 - 2.75 ---- 2.85

💡 Estimate First

• Round numbers to nearest whole number to guess the answer.
• Helps check if the final answer is reasonable.

📚 Solve Step by Step

• Step 1: Identify the numbers.
• Step 2: Decide operation (+ or -).
• Step 3: Line up decimals.
• Step 4: Solve carefully.
• Step 5: Write the answer with correct units (kg, m, $, etc.).

✅ Common Mistakes to Avoid

• Forgetting to align decimals. ❌
• Forgetting place value after decimal. ❌
• Ignoring units in the answer. ❌

🎯 Practice Word Problems

• Example 1: A bottle contains 3.45 L of juice. 1.75 L is poured into glasses. How much juice is left?
• Example 2: Sam ran 2.8 km on Monday and 3.65 km on Tuesday. How far did he run in total?

Learn with an example