Place Value, Rounding & Estimation
Understand place value in whole numbers and decimals, round to a required accuracy, and use estimation to check answers.
Overview
Place value is the value a digit has because of its position in a number. In Year 7 students extend place value to decimals, learn to round numbers to the nearest 10, 100, 1000 or to a number of decimal places, and use estimation to check whether an answer is sensible. Rounding and estimating are skills examiners reward throughout the whole programme.
What You Will Learn
- State the value of any digit in a whole number or decimal
- Multiply and divide whole numbers and decimals by 10, 100 and 1000
- Round whole numbers to the nearest 10, 100 or 1000
- Round decimals to a given number of decimal places
- Estimate the answer to a calculation by rounding each number to 1 significant figure
Key Vocabulary
Common Mistakes to Avoid
- Rounding 4.48 to 1 decimal place as 4.5 by rounding twice instead of looking only at the next digit
- Forgetting that a 5 rounds up
- Moving the decimal point the wrong way when dividing by 10 or 100
- Dropping the zero in numbers like 3.40 when it is needed to show the accuracy
What Comes Next
Year 8 builds on this with rounding to significant figures and standard form for very large and very small numbers. Accurate rounding and estimation are expected on every IGCSE paper.
Frequently Asked Questions
What is the difference between rounding and estimating?
Rounding changes one number to a nearby simpler value. Estimating uses rounding on every number in a calculation so you can quickly check whether your exact answer is sensible.
Why do we estimate if we can use a calculator?
Estimating catches mistakes. If your calculator answer is wildly different from your estimate, you know you have pressed a wrong button somewhere.
Study This Topic
Topic Details
- Stage
- Year 7
- Strand
- Number
- Framework ref
- 7Np
- Difficulty
- Low
Build strong foundations in Place Value, Rounding & Estimation
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Heading toward IGCSE? See how Place Value, Rounding & Estimation develops in IGCSE Number (Cambridge 0580) →