Transcript Approximation Estimation

Chapter 3
Approximation & Estimation
Learning Outcomes
Round to nearest 10, 100, 1000
Round in practical problems
Round to a specified number of decimal
places
Round to a specified number of significant
figures
Choosing a degree of accuracy for the answer
that suits the question
Estimating calculations
Rounding to nearest 10, 100,…
If 5 or above round up
 If below 5 leave alone
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Number
7834
8323
20911
90892
9999
Nearest
10
Nearest
100
Nearest
1000
Practical Problems

Remember to think if your answer is
sensible!!!!
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Example
A year group are going on a trip to Paris. There are
242 students going. Each bus holds 55
passengers. How many buses are needed?
Rounding Decimals

Start counting after the decimal place
Number 1 dp
2.7849
2.34535
0.0234
0.99999
2 dp
3 dp
4 dp
Significant Figures

Start counting at the 1st non-zero digit
Number 1 sf
2.7849
234.535
0.0234
99.999
2 sf
3 sf
4 sf
Choosing a Degree of Accuracy
Use common sense!!!
 If answer is in metres use 2 dp
 If a question is given to 1 dp the answer
should be given to 1 dp
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Estimation

When estimating a calculation use 1
significant figure or round to numbers that
give even answers
Examples
1) Estimate 432 × 29
2) Estimate (49.7 + 10.6) ÷ (9.69 × 3.04)
3) Estimate 78.9 ÷ (0.037 × 5.2)
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