Round Decimals

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Answer Key & Explanations

Round Decimals · Grade 4 · Worksheet 3

1. Round 6.84 to the nearest tenth = ? Answer: 6.8 Solution: Identify the digit in the tenths place. In 6.84, the digit in the tenths place is 8. Identify the digit in the hundredths place.
   Full step-by-step solution

   Step 1: Identify the digit in the tenths place. In 6.84, the digit in the tenths place is 8. Step 2: Identify the digit in the hundredths place. In 6.84, the digit in the hundredths place is 4. Step 3: Since the hundredths digit (4) is less than 5, we do not round the tenths digit up. The tenths digit remains 8. Step 4: The digits after the tenths place become zero, so 6.84 rounded to the nearest tenth is 6.8. The answer is 6.8.

2. Hana is drawing a rectangular playground on a grid. The playground is 14.6 meters long and 8.2 meters wide. She wants to mark the perimeter with a fence. What is the perimeter of the playground? Round your answer to the nearest whole number. Answer: 46 Solution: The perimeter of a rectangle is found by adding all four sides: 2 x length + 2 x width. First, add the length and width: 14.6 + 8.2 = 22.8. Multiply by 2 (since there are two lengths and two widths): 22.8 x 2 = 45.6.
   Full step-by-step solution

   Step 1: The perimeter of a rectangle is found by adding all four sides: 2 x length + 2 x width. Step 2: First, add the length and width: 14.6 + 8.2 = 22.8. Step 3: Multiply by 2 (since there are two lengths and two widths): 22.8 x 2 = 45.6. Step 4: Now round 45.6 to the nearest whole number. Look at the tenths digit: it is 6, which is 5 or more, so we round up. Step 5: 45.6 rounds to 46. The answer is 46.

3. Mason is helping his dad measure the weight of fruit at their farm stand. A large pumpkin weighs 12.68 pounds. To make it easier for customers, Mason needs to round the weight to the nearest tenth of a pound. What is the weight of the pumpkin rounded to the nearest tenth? Answer: 12.7 pounds Solution: Identify the place to round to - the nearest tenth. The tenths place is the first digit after the decimal, which is 6 (in 12.68). Look at the digit to the right of the tenths place - the hundredths place.
   Full step-by-step solution

   Step 1: Identify the place to round to - the nearest tenth. The tenths place is the first digit after the decimal, which is 6 (in 12.68). Step 2: Look at the digit to the right of the tenths place - the hundredths place. That digit is 8. Step 3: Since 8 is greater than or equal to 5, we round the tenths digit up. The 6 becomes 7. Step 4: The whole number part (12) stays the same. The rounded number is 12.7 pounds. Answer: 12.7 pounds

4. Emma is baking cookies for her school bake sale. She needs 2.75 cups of flour for the chocolate chip cookies and 1.25 cups of flour for the sugar cookies. How many cups of flour does Emma need in total? Answer: 4.00 Solution: Identify the amounts: 2.75 cups for chocolate chip cookies and 1.25 cups for sugar cookies. Write the addition problem: 2.75 + 1.25 2.75 + 1.25 Add the hundredths place: 5 + 5 = 10.
   Full step-by-step solution

   Step 1: Identify the amounts: 2.75 cups for chocolate chip cookies and 1.25 cups for sugar cookies. Step 2: Write the addition problem: 2.75 + 1.25 Step 3: Line up the decimal points and add: 2.75 + 1.25 ------- Step 4: Add the hundredths place: 5 + 5 = 10. Write 0 in the hundredths place, carry over 1 to the tenths place. Step 5: Add the tenths place: 7 + 2 + 1 (carried over) = 10. Write 0 in the tenths place, carry over 1 to the ones place. Step 6: Add the ones place: 2 + 1 + 1 (carried over) = 4. Step 7: Place the decimal point in the answer: 4.00 Emma needs 4.00 cups of flour in total.

5. Noah is measuring the length of a caterpillar he found in his backyard. The caterpillar is 3.61 inches long. Noah's little sister Ava wants to know the length rounded to the nearest whole inch. What should Noah tell her? Answer: 4 Solution: Identify the place value to round to: the nearest whole number (ones place). Look at the digit in the tenths place, which is 6 (since 3.61 has 6 tenths).
   Full step-by-step solution

   Step 1: Identify the place value to round to: the nearest whole number (ones place). Step 2: Look at the digit in the tenths place, which is 6 (since 3.61 has 6 tenths). Step 3: The rule for rounding is: if the tenths digit is 5 or greater, round up the ones digit. If it is less than 5, keep the ones digit the same. Step 4: Since 6 is greater than 5, we round up the ones digit from 3 to 4. Step 5: The caterpillar's length rounded to the nearest whole inch is 4 inches. Answer: 4

6. Aroha is measuring the height of a plant in her garden. On Monday, the plant is 7.83 centimeters tall. On Friday, it has grown to 9.17 centimeters. What is the height of the plant on Friday rounded to the nearest whole centimeter? Answer: 9 Solution: The height on Friday is 9.17 centimeters. We need to round this to the nearest whole number. Step 2: Look at the digit in the tenths place, which is 1.
   Full step-by-step solution

   Step 1: The height on Friday is 9.17 centimeters. We need to round this to the nearest whole number. Step 2: Look at the digit in the tenths place, which is 1. Step 3: Since 1 is less than 5, we round down, meaning the whole number stays the same. Step 4: So 9.17 rounded to the nearest whole number is 9. The answer is 9.

7. Round 136.1 to the nearest whole number = ? Answer: 136 Solution: Identify the digit in the ones (whole number) place: 136.1 has 6 in the ones place. Look at the digit in the tenths place: 136.1 has 1 in the tenths place. Since 1 is less than 5, we do not round up.
   Full step-by-step solution

   Step 1: Identify the digit in the ones (whole number) place: 136.1 has 6 in the ones place. Step 2: Look at the digit in the tenths place: 136.1 has 1 in the tenths place. Step 3: Since 1 is less than 5, we do not round up. The ones digit stays 6. Step 4: The number 136.1 rounded to the nearest whole number is 136. The answer is 136.