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Number Sense and Numeration. Rounding Numbers. Often in real life we don’t use exact numbers to describe the quantities of things, instead we use numbers that are rounded up or down from the original number This is done for a few reasons:
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Number Sense and Numeration Rounding Numbers
Often in real life we don’t use exact numbers to describe the quantities of things, instead we use numbers that are rounded up or down from the original number • This is done for a few reasons: • Rounded numbers are easier to take in and remember at a glance • In some cases, numbers fluctuate (change), and using rounded numbers in this case is more appropriate because it is difficult to pin down the exact number at all times Numbers in Real Life
Now that we understand that parts of numbers have different place values, we can use that information to help us round numbers in different ways • We can round numbers to the nearest ten, hundred, thousand, or ten thousand • Remember, if the number to the right of the number we are rounding (no matter what place value it is) is 5 or higher, we round up and if it is 4 or lower, we round down (the number stays the same) Different ways of rounding numbers
Round this number to the nearest ten thousand:38 495 • Now round it to the nearest thousand • Now round it to the nearest hundred • And lastly, round it to the nearest ten Practise with Rounding to Different Place Values
Number lines can provide a valuable visual for rounding...rather than having to look at specific numbers, you can plot the whole number on the line and see where it would be most appropriately rounded to • For example, if you were asked to round the number 6584 to the nearest thousand, you could plot 6000 and 7000 at either end of a number line and plot 6584 on the line between them to see which it is closest to Using number lines to round
The following shows what that would look like: 6584 6000 6500 7000 • As you can see, 6584 is slightly closer to 7000, therefore that would be your answer when rounding to the nearest thousand Using Number Lines to Round continued...
Read through Jasleen’s Rounding investigation on page 36 in the text book and complete questions A, B, C and D • Complete “Practising” questions #s 5 and 6 On Your Own