Rounding Numbers

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Answer Key & Explanations

Rounding Numbers · Grade 3 · Worksheet 3

1. Round 1305 to the nearest 100. Answer: 1300 Solution: Look at the digit that decides rounding to the nearest 100. 1305 rounds to 1300.
   Full step-by-step solution

   Step 1: Look at the digit that decides rounding to the nearest 100. Step 2: 1305 rounds to 1300. The answer is 1300.

2. Round 649 to the nearest 100. Answer: 600 Solution: Look at the digit that decides rounding to the nearest 100. 649 rounds to 600.
   Full step-by-step solution

   Step 1: Look at the digit that decides rounding to the nearest 100. Step 2: 649 rounds to 600. The answer is 600.

3. A rectangular swimming pool is drawn on grid paper. The pool is 25 meters long and 15 meters wide. If you count all the 1-meter by 1-meter squares that make up the pool's floor, how many squares are there? Answer: 375 Solution: The pool is a rectangle with length 25 meters and width 15 meters. Each 1-meter by 1-meter square represents one unit of area.
   Full step-by-step solution

   Step 1: The pool is a rectangle with length 25 meters and width 15 meters. Step 2: Each 1-meter by 1-meter square represents one unit of area. Step 3: To find the total number of squares, multiply the length by the width: 25 × 15 Step 4: First multiply 25 × 10 = 250 Step 5: Then multiply 25 × 5 = 125 Step 6: Add the results: 250 + 125 = 375 Step 7: There are 375 one-meter squares in the pool's floor.

4. Liam is collecting baseball cards. He has 75 cards in his collection. For his birthday, his grandmother gives him a special set that contains 25 more cards. How many baseball cards does Liam have now? Answer: 100 Solution: Identify how many baseball cards Liam starts with. Liam has 75 cards in his collection. Identify how many new cards he receives.
   Full step-by-step solution

   Step 1: Identify how many baseball cards Liam starts with. Liam has 75 cards in his collection. Step 2: Identify how many new cards he receives. His grandmother gives him a special set containing 25 more cards. Step 3: Add the new cards to the original number of cards. 75 + 25 = ? Step 4: Perform the addition. First, add the ones place: 5 + 5 = 10. Write down 0, carry over 1 to the tens place. Then, add the tens place: 7 + 2 = 9, plus the carried over 1 gives 10. So, 75 + 25 = 100. Step 5: State the final answer. Liam now has 100 baseball cards.

5. A rectangular garden is drawn on grid paper. It has a length of 12 units and a width of 8 units. If you count all the 1-unit by 1-unit squares inside the rectangle, how many squares are there? Answer: 96 Solution: We are told the garden is a rectangle with length 12 units and width 8 units. We want the number of 1-unit by 1-unit squares inside it.
   Full step-by-step solution

   We are told the garden is a rectangle with length 12 units and width 8 units. We want the number of 1-unit by 1-unit squares inside it. Step 1: Understand the grid. The rectangle is drawn on grid paper, so along the length there are 12 small squares in a row. Along the width there are 8 small squares in a column. Step 2: Find the total number of 1×1 squares. Each small square is 1 unit by 1 unit. To find the total number of such squares, we multiply the number of squares along the length by the number of squares along the width. So: Total squares = length × width Total squares = 12 × 8 Step 3: Perform the multiplication. 12 × 8 = 96 Step 4: Interpret the result. This means there are 96 small 1×1 unit squares inside the rectangle. Final answer: 96