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Estimating a Quantity and Approximating a Result - Cycle 1
| Mathematics
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Estimating a quantity means guessing how many objects or people there are in a set without counting them.
In the following figure, we can see that there are lots of spiders.
Before counting them one by one, we can estimate how many we think there are. In this image, it looks like there are around 50 spiders. That’s our estimate.
Now, we count them one by one. We get a total of 56 spiders. This is the exact value.
Our estimate is fairly close to the exact value. So, we made a good estimate.
We can also estimate a measurement of length, time, or temperature.
Here are a few examples:
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An ice cream cone is about 10 cm tall.
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You’re hungry and know that lunch will be ready soon, so it must be around noon.
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It’s warm enough that I can go outside in a bathing suit, so the temperature must be around 25°C.
Approximating the result of a calculation means finding a number close to the exact answer.
For example, to find the approximate result of a complex addition problem, we can round the numbers before adding them.
To learn how to round a number, read the concept sheet Rounding a Number.
Stacy picks pears with her grandmother. Stacy picked 316 pears and her grandmother picked 588. Approximately how many pears did Stacy and her grandmother pick in total?
Before adding the two numbers, we’ll round them to the nearest hundred.
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316 is between 300 and 400, but closer to 300, so we know that 316 rounded to the nearest hundred is 300. |
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588 is between 500 and 600, but closer to 600, so we know that 588 rounded to the nearest hundred is 600. |
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316 + 588 |
Answer: Stacy and her grandmother picked approximately 900 pears in total.