Estimate and check
Objective. Use rounding to estimate calculations and test whether answers are sensible.
- 1. Learn
- 2. Worked example
- 3. Practice
- 4. Feedback
- 5. Continue
Learn: the key idea
Estimate and check is built on a small number of dependable facts. Read, compare, order and estimate with integers and decimals. Represent the information first, choose a method deliberately, show each step and use an inverse operation or estimate to check that the result fits the question.
Worked example
Complete the place-value statement.
- 1Identify the mathematical information and what must be found.
- 2Represent it with a number line, diagram, table or expression where helpful.
- 3Apply the relevant fact carefully and keep each line clear.
- 4Check the result against the conditions in the question: 6000.
Answer: 6000
Concept mastery
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Practice
Practice happens on its own screen, one question at a time. Answers stay hidden until you submit yours, and you can stop and pick up at the same question later.
Start practisingCommon mistake. A common mistake in estimate and check is to apply a remembered procedure before reading the signs, units or order carefully. Write the structure first, then calculate and check.
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