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What is the cost of 14.6 gallons[br]of gasoline at $2.70

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per gallon?

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So we have 14.6 gallons,[br]and each gallon's

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going to cost $2.70.

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Or we can even view $2.70[br]as 2.7 dollars.

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Let's just multiply times 2.7.

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It makes things a little[br]bit simpler.

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I think you'll appreciate $2.70[br]is the same thing as 2.7

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dollars per gallon.

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So let's multiply this out.

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So first we have, and just as a[br]reminder, when you multiply

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decimals, you just have to treat[br]the numbers like whole

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numbers and then worry about[br]the decimals later.

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So right now, we can just view[br]this as 146 times 27, and then

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we'll worry about[br]the decimals.

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So first we have[br]a 7 times a 6.

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7 times 6 is 42.

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Regroup the 4.

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7 times 4 is 28, plus 4 is 32.

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Regroup the 3.

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7 times 1 is 7, plus 3 is 10.

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So we get 7 times[br]146 is 1,022.

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Now we're going to[br]deal with this 2.

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But this 2, at least before we[br]consider the decimal, is

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really a 20.

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So we're going to[br]put a 0 here.

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We're doing it exactly the same[br]way we do a traditional

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multiplication problem.

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We're ignoring the[br]decimals for now.

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2 times 6 is 12.

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Carry the 1, or regroup the 1.

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We can ignore these[br]guys right now.

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2 times 4 is 8, plus 1 is 9.

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2 times 1 is 2, and[br]now we can add.

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And we get 2 plus 0 is 2.

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2 plus 2 is 4.

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0 plus 9 is 9.

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1 plus 2 is 3.

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Now we've figured out what[br]146 times 27 is.

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It's 3,942.

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But this wasn't 146 times 27.

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It was 14.6 times 2.7.

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So now we have to worry[br]about the decimals.

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We just count how many numbers[br]are sitting behind decimals.

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We have one right there and[br]a second one right there.

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So our product has to have[br]two numbers to the

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right of the decimal.

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So one, two, stick it[br]right over there.

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So for 14.6 gallons of gas at[br]$2.70 per gallon, it's going

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to cost $39.42.

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