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Published byAlvin Trow Modified over 10 years ago
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LO: To be able to round numbers Mrs Vivien Criddle Westfield Middle School
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What is rounding? Sometimes we want to add numbers in our head but the numbers are a bit tricky. We can estimate (take a good guess) the answer It is easier if we use numbers that are in 10s Rounding means we find the nearest 10
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Up or Down 1, 2, 3, 4 5, 6, 7, 8, 9 Does the number end in… Round down Round up
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Lets look at a number line… Where do these numbers go? 21 39 64 83
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Let’s take a closer look… 21 Is 21 closer to 20 or 30? Does it end in 1, 2, 3 or 4?
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Round down!
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Another close look… 39 Is 39 closer to 30 or 40? Does it end in 5, 6, 7, 8 or 9?
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Round up!
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Another close look… 64 Is 64 closer to 60 or 70? Does it end in 1, 2, 3 or 4?
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Round down!
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Another close look… 83 Is 83 closer to 80 or 90? Does it end in 1, 2, 3 or 4?
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Round down!
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Your turn Use your whiteboard Draw an arrow on it Show me… Round up Round down
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32
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Round down!
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97
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Round up!
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5
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71
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Round down!
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