Flashcards · Maths · Standard Form and Accuracy
Rounding and Estimating
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How do you round to 1 decimal place?
Look at the second decimal digit: 5 or more rounds up, and 4 or less rounds down.
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What is 4.678 to 1 d.p.?
4.7.
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What is a significant figure?
A digit that counts, starting from the first non-zero digit.
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What is 0.004567 to 2 s.f.?
0.0046.
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What is 6482 to 2 s.f.?
6500.
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What is 83.7 to the nearest 10?
80.
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What is 87.2 to the nearest 10?
90.
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How do you estimate a calculation?
Round each number to 1 significant figure, then calculate.
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What does \(\approx\) mean?
Approximately equal to.
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What is an estimate for \(\dfrac{4.97 \times 20.1}{0.49}\)?
\(\dfrac{5 \times 20}{0.5} = 200\).
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If the bottom of a fraction is rounded up, what happens to the answer?
The answer gets smaller.
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If the top of a fraction is rounded up, what happens to the answer?
The answer gets bigger.
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Why show the rounded numbers?
They show the method, and earn the marks.
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Do zeros at the start of a decimal count as significant figures?
No.
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Which digit decides whether to round up?
The one just after the place you are rounding to.
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What should you write after a rounded answer?
The accuracy, such as "to 2 s.f.".