Add/Subtract Decimals

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Answer Key & Explanations

Add/Subtract Decimals · Grade 4 · Worksheet 2

1. Emma is saving money for a new bicycle. She already has $125.75 saved from her allowance. For her birthday, her grandparents give her $50.25. How much money does Emma have now for her bicycle? Answer: 176.00 Solution: Start with the amount Emma already had: $125.75 Add the birthday money from her grandparents: $50.25 Add the dollars: 125 + 50 = 175 dollars Add the cents: 75 cents + 25 cents = 100 cents Convert 100 cents to 1 dollar: 175 dollars + 1 dollar = 176 dollars Write as dollars and cents: $176.00 Emma…
   Full step-by-step solution

   Step 1: Start with the amount Emma already had: $125.75 Step 2: Add the birthday money from her grandparents: $50.25 Step 3: Add the dollars: 125 + 50 = 175 dollars Step 4: Add the cents: 75 cents + 25 cents = 100 cents Step 5: Convert 100 cents to 1 dollar: 175 dollars + 1 dollar = 176 dollars Step 6: Write as dollars and cents: $176.00 Emma now has $176.00 for her bicycle.

2. Harper had 17 dollars. Then Harper spent 7 dollars at the store. How much money does Harper have left? Answer: 10 Solution: Start with 17 dollars. Subtract the amount spent: 17 - 7 = 10. Harper has 10 dollars left.
   Full step-by-step solution

   Step 1: Start with 17 dollars. Step 2: Subtract the amount spent: 17 - 7 = 10. Harper has 10 dollars left.

3. 23.45 + 17.68 = ? Answer: 41.13 Solution: 23.45 + 17.68 Add the hundredths place: 5 + 8 = 13. Write 3, carry over 1 to tenths place. Add the tenths place: 4 + 6 + 1 (carry) = 11.
   Full step-by-step solution

   Step 1: Write the numbers with decimal points aligned: 23.45 + 17.68 Step 2: Add the hundredths place: 5 + 8 = 13. Write 3, carry over 1 to tenths place. Step 3: Add the tenths place: 4 + 6 + 1 (carry) = 11. Write 1, carry over 1 to ones place. Step 4: Add the ones place: 3 + 7 + 1 (carry) = 11. Write 1, carry over 1 to tens place. Step 5: Add the tens place: 2 + 1 + 1 (carry) = 4. Step 6: Bring down the decimal point. Final answer: 41.13

4. Liam is measuring ribbon for a craft project. He needs 2.75 meters of blue ribbon and 1.5 meters of red ribbon. How many meters of ribbon does Liam need in total? Answer: 4.25 Solution: Liam needs two pieces of ribbon: blue and red. Write down the lengths he needs. Blue ribbon: 2.75 meters Red ribbon: 1.5 meters To find the total, add the two lengths together.
   Full step-by-step solution

   Liam needs two pieces of ribbon: blue and red. Step 1: Write down the lengths he needs. Blue ribbon: 2.75 meters Red ribbon: 1.5 meters Step 2: To find the total, add the two lengths together. Total = 2.75 + 1.5 Step 3: Align the numbers by their decimal points to add them. 2.75 + 1.50 _______ Step 4: Add the numbers column by column, starting from the right. First, add the hundredths column: 5 + 0 = 5. Write down 5. Next, add the tenths column: 7 + 5 = 12. Write down 2 and carry over the 1 to the ones column. Finally, add the ones column: 2 + 1 + 1 (the carried over number) = 4. Write down 4. Step 5: Combine the results. The total is 4.25. So, Liam needs 4.25 meters of ribbon in total.

5. A rectangular swimming pool is drawn on a blueprint. The longer sides measure 12.25 meters each and the shorter sides measure 8.75 meters each. What is the total distance around the entire pool? Answer: 42 Solution: Identify the lengths of the sides. Longer side = 12.25 m (there are 2 of these) Shorter side = 8.75 m (there are 2 of these) Multiply each side length by 2 and add them.
   Full step-by-step solution

   Step 1: Identify the lengths of the sides. Longer side = 12.25 m (there are 2 of these) Shorter side = 8.75 m (there are 2 of these) Step 2: Multiply each side length by 2 and add them. Perimeter = 2 × (longer side) + 2 × (shorter side) Perimeter = 2 × 12.25 + 2 × 8.75 Step 3: Calculate 2 × 12.25 2 × 12.25 = 24.50 Step 4: Calculate 2 × 8.75 2 × 8.75 = 17.50 Step 5: Add the two results 24.50 + 17.50 = 42.00 Step 6: State the final answer The total distance around the entire pool is 42 meters.

6. A rectangular swimming pool is drawn with a length of 15.25 meters and a width of 9.5 meters. A decorative tile border is installed around the entire edge of the pool. What is the total length of the tile border in meters? Answer: 49.5 Solution: Recall the formula for the perimeter of a rectangle. Perimeter = 2 × (length + width) Substitute the given values into the formula. Perimeter = 2 × (15.25 + 9.5) Add the length and width.
   Full step-by-step solution

   Step 1: Recall the formula for the perimeter of a rectangle. Perimeter = 2 × (length + width) Step 2: Substitute the given values into the formula. Perimeter = 2 × (15.25 + 9.5) Step 3: Add the length and width. 15.25 + 9.5 = 24.75 Step 4: Multiply by 2. 2 × 24.75 = 49.5 Step 5: State the final answer. The total length of the tile border is 49.5 meters.

7. On a nature walk, Moana found 24 feet of a hiking trail. Then Moana found another 50 feet of the trail. How many total feet of the trail did Moana find? Answer: 74 Solution: Start with 24 feet. Add the second part: 24 + 50 = 74. Moana found a total of 74 feet of the trail.
   Full step-by-step solution

   Step 1: Start with 24 feet. Step 2: Add the second part: 24 + 50 = 74. Moana found a total of 74 feet of the trail.