Round Decimals

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Answer Key & Explanations

Round Decimals · Grade 5 · Worksheet 1

1. Round 8.495 to the nearest hundredth. Answer: 8.50 Solution: Identify the hundredths place and the thousandths place. In 8.495, the digit in the hundredths place is 9, and the digit in the thousandths place is 5.
   Full step-by-step solution

   Step 1: Identify the hundredths place and the thousandths place. In 8.495, the digit in the hundredths place is 9, and the digit in the thousandths place is 5. Step 2: Since the digit in the thousandths place is 5 or greater, we round the hundredths place up. Step 3: Rounding the 9 up changes it to 10. This means the 9 becomes 0, and we add 1 to the tenths place. Step 4: The tenths place digit is 4. Adding 1 makes it 5. Step 5: The number becomes 8.50. The answer is 8.50.

2. Maria is tracking the growth of her sunflower plant for a science project. After 30 days, her plant has grown to 4.637 meters tall. She needs to report the height rounded to the nearest hundredth of a meter in her project journal. What height should Maria record? Answer: 4.64 Solution: Identify the hundredths place in 4.637. The digits are: 4 (ones), . (decimal point), 6 (tenths), 3 (hundredths), 7 (thousandths).
   Full step-by-step solution

   Step 1: Identify the hundredths place in 4.637. The digits are: 4 (ones), . (decimal point), 6 (tenths), 3 (hundredths), 7 (thousandths). Step 2: Since we're rounding to the nearest hundredth, we look at the thousandths place digit, which is 7. Step 3: Because 7 is greater than or equal to 5, we round the hundredths place digit (3) up by 1. Step 4: 3 in the hundredths place becomes 4, and we drop the thousandths place. Step 5: The rounded number is 4.64 meters. The answer is 4.64.

3. A scientist is measuring the growth of a special crystal. After 7 days, the crystal has grown to 3.8276 centimeters. Round this measurement to the nearest hundredth of a centimeter. Answer: 3.83 Solution: Identify the digit in the hundredths place. The number is 3.8276. 8 (tenths), 2 (hundredths), 7 (thousandths), 6 (ten-thousandths).
   Full step-by-step solution

   Step 1: Identify the digit in the hundredths place. The number is 3.8276. The digits after the decimal point represent: 8 (tenths), 2 (hundredths), 7 (thousandths), 6 (ten-thousandths). So the hundredths digit is 2. Step 2: Look at the digit immediately to the right of the hundredths place. That digit is 7, which is in the thousandths place. Step 3: Apply the rounding rule: If the thousandths digit is 5 or greater, round the hundredths digit up by 1. If it is less than 5, keep the hundredths digit the same. Here, the thousandths digit is 7, which is greater than or equal to 5, so we round the hundredths digit (2) up to 3. Step 4: Write the rounded number. All digits to the left of the hundredths place remain the same: 3.8 The hundredths place becomes 3, and we drop all digits after it. So 3.8276 rounded to the nearest hundredth is 3.83. Final Answer: 3.83

4. A rectangular prism has a length of 8.5 cm, a width of 6.2 cm, and a height of 4.7 cm. What is the volume of the prism? Answer: 247.69 Solution: To find the volume of a rectangular prism, we multiply its length, width, and height. Write down the formula for volume. Volume = length × width × height Substitute the given values into the formula.
   Full step-by-step solution

   To find the volume of a rectangular prism, we multiply its length, width, and height. Step 1: Write down the formula for volume. Volume = length × width × height Step 2: Substitute the given values into the formula. Length = 8.5 cm Width = 6.2 cm Height = 4.7 cm Volume = 8.5 × 6.2 × 4.7 Step 3: Perform the multiplication step by step. First, multiply the length and the width. 8.5 × 6.2 To do this, first multiply 85 × 62. 85 × 60 = 5100 85 × 2 = 170 Add them: 5100 + 170 = 5270 Since we multiplied 85 and 62 (instead of 8.5 and 6.2), we have one decimal place in 8.5 and one decimal place in 6.2, so the total is two decimal places. Therefore, 5270 becomes 52.70. So, 8.5 × 6.2 = 52.7 Step 4: Now multiply this result by the height. 52.7 × 4.7 To do this, first multiply 527 × 47. 527 × 40 = 21080 527 × 7 = 3689 Add them: 21080 + 3689 = 24769 Since we multiplied 527 and 47 (instead of 52.7 and 4.7), we have one decimal place in 52.7 and one decimal place in 4.7, so the total is two decimal places. Therefore, 24769 becomes 247.69. Step 5: State the final answer. The volume of the rectangular prism is 247.69 cubic centimeters. Answer: 247.69

5. Aroha is helping her family measure the wood for a new garden planter box. The piece of wood she is measuring is 7.853 meters long. Her father asks her to record the length rounded to the nearest tenth of a meter for the building plan. What length should Aroha write down? Answer: 7.9 Solution: Identify the tenths place in 7.853. The tenths place is the first digit after the decimal point, which is 8. Look at the digit immediately to the right of the tenths place, which is the hundredths place.
   Full step-by-step solution

   Step 1: Identify the tenths place in 7.853. The tenths place is the first digit after the decimal point, which is 8. Step 2: Look at the digit immediately to the right of the tenths place, which is the hundredths place. That digit is 5. Step 3: Since 5 is equal to 5, we round the tenths place up from 8 to 9. Step 4: All digits to the right of the tenths place become zero, so the rounded number is 7.9. The answer is 7.9.

6. Round 8.475 to the nearest tenth. Answer: 8.5 Solution: Identify the digit in the tenths place. In 8.475, the tenths digit is 4. Look at the digit to the right (the hundredths place), which is 7.
   Full step-by-step solution

   Step 1: Identify the digit in the tenths place. In 8.475, the tenths digit is 4. Step 2: Look at the digit to the right (the hundredths place), which is 7. Step 3: Since the hundredths digit (7) is 5 or greater, we round the tenths digit (4) up by 1, making it 5. Step 4: The digits after the tenths place become zero, so 8.475 rounded to the nearest tenth is 8.5.

7. Maria is tracking the growth of her sunflower plant for a science project. After 3 weeks, her plant has grown to 4.837 meters tall. She needs to record this measurement rounded to the nearest hundredth of a meter in her project journal. What height should Maria write down? Answer: 4.84 Solution: Identify the hundredths place in 4.837. The digits are: 4 (ones), 8 (tenths), 3 (hundredths), 7 (thousandths). Look at the digit immediately after the hundredths place, which is 7 in the thousandths place.
   Full step-by-step solution

   Step 1: Identify the hundredths place in 4.837. The digits are: 4 (ones), 8 (tenths), 3 (hundredths), 7 (thousandths). Step 2: Look at the digit immediately after the hundredths place, which is 7 in the thousandths place. Step 3: Since 7 is greater than or equal to 5, we round the hundredths place up from 3 to 4. Step 4: The rounded number becomes 4.84 meters. The answer is 4.84.