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52 plus 29 equals what?
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The number 29 is one less than 30.
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We could round 29 to 30 by adding one.
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Then, we could work out what 52 plus 30 is.
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The ones digit doesn’t change because 30 has no ones.
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Two plus nothing is two.
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Now, we need to add the tens.
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Five tens and three tens makes eight tens which is 80.
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80 plus two is 82.
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So 52 plus 30 is 82.
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But the question doesn’t ask us to add 30.
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It asks us to add 29.
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We’ve added one too many because we rounded 29 to 30.
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So we need to take away one from 82, which gives us a total of 81.
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52 plus 29 equals 81.