Approximation & estimation · Ages 12–13
Rounding to decimal places
Look at the next decimal place; write every decimal place asked for.
How to do it
Method
Look at the next decimal place; write every decimal place asked for
2.4371 ≈ 2.44 (to 2 d.p.)
Another way
Count in hundredths
2.4371 = 243.71 hundredths ≈ 244 hundredths = 2.44
In full
"Correct to 2 decimal places" keeps two digits after the point: correct to the nearest hundredth. Look at the third decimal place: 5 or more adds 1 to the second, otherwise it stays, and every digit after it goes. 2.4371 to 2 d.p.: the third digit is 7, so 2.44. Rounding up can carry: 5.397 to 2 d.p. is 5.40, and the answer is written with two decimal places. The final 0 stays, because 5.4 is correct to 1 d.p. only. Or count in units: to 2 d.p. means in units of 0.01. 2.4371 is 243.71 hundredths, which rounds to 244 hundredths, 2.44.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
The arrow points to a number. What is it correct to 1 decimal place?
- A. 6.6
- B. 6.59
- C. 6.5
- D. 6.55
Choose the right answer
Show the answer and working
Answer: A. 6.6
The arrow is at 6.59. Look at the second decimal place: 5 or more rounds up, otherwise it drops. So 6.6.
Example 2
5.5782 correct to 2 decimal places: the third decimal place is , so the answer is .
Fill in each blank
Show the answer and working
Answer: 8, 5.58
The third decimal place is 8: 5 or more adds 1 to the second, otherwise it stays. So 5.58.
Example 3
0.02353 correct to the nearest thousandth (3 decimal places) is .
Show the answer and working
Answer: 0.024
The thousandths are the third decimal place; look at the fourth, 5: 5 or more rounds up, otherwise it drops. So 0.024.
Practice questions to try
Try these 5; the answers are at the end. For a whole worksheet, see VIP worksheets below.
1.34.365 correct to 2 decimal places is 34.37.
True or false?
Answer:
2.5.8443 correct to 2 decimal places is .
Answer:
3.3.08844 correct to 3 decimal places is .
Answer:
4.34.958 correct to 1 decimal place is .
Answer:
5.0.02555 correct to the nearest thousandth (3 decimal places) is .
Answer:
All the answers
- 1. True
- 2. 5.84
- 3. 3.088
- 4. 35
- 5. 0.026
VIP practice notes and papers
Aimed at tests and exams: questions on this topic, new every time, to print or save as a PDF.
- Practice notes: The key point, worked examples step by step, then questions of the same kind to follow, hints fading
- Practice paper: Set out in parts like a school paper, marked, with answers and full working
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