In this section we will look at how we round numbers to a given accuracy.
We need to remind ourselves about the idea of place value in any particular number.
The "4" in the number above is actually worth 40000, because the place value of its position is ten-thousand (10000).
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Think about the number 7451. We want to write this number to the "nearest ten".
The two "nearest tens" to 7451 are 7450 (below) and 7460 (above). The diagram below shows this: We can easily see now that 7450 is the "nearest ten", so 7451 to the nearest 10 is 7450. |
Now we want to write 7451 to the "nearest hundred".
Look at this diagram which shows the "nearest hundreds" to 7451: We can see that 7451 to the nearest 100 is 7500. |
Finally, we want to write 7451 to the "nearest thousand".
The "nearest thousands" to 7451 are 7000 and 8000, as shown below: We can see that 7451 to the nearest 1000 is 7000. |
For example, imagine rounding 350 to the nearest 100.
The diagram shows that 350 is exactly halfway between 300 and 400: The "5" always rounds up, so 350 to the nearest 100 is 400. |
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