WEBVTT
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Which of the following is closest to five times 103 times 60?
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Solve without using a calculator.
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We have options 30000, 300000, 40000, or 3000.
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So here we’re looking at simplifying five times 103 times 60, and we’re not allowed to use a calculator.
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But it asks us which of the following is closest to that.
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So that means it would be okay to round a little bit.
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So the fact that 103 is so close to 100, we will go ahead and change it to 100.
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So, solving this without a calculator, what looks easiest so far is five times 100.
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That just means we need five 100s.
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So 100 plus 100 plus 100 plus 100 plus 100 is equal to 500.
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However, we still need to multiply 500 and 60 together.
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So since we can’t use a calculator, there are three zeros involved, and we’ll use that in a minute.
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But we can use the fact that five times six is 30.
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And then we need to add three more zeros.
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It’s a nice little trick.
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So we get 30000.
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So 30000 will be our final answer.
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We also could’ve done this a little bit differently.
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Maybe instead we would multiply 60 and 100 together first.
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Well, there are three zeros, and we have a one and a six.
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And one times six is six, and then we add the three zeros.
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So now we take that number and multiply it by five.
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Well, we take five times six, which is 30, and then add the three zeros.
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And once again, we get 30000.
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So we would choose option A 30000.