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A ticket agent sells 42 tickets to a play.

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The tickets cost $29 each.

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Use rounding to estimate the total dollars taken in from

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the sale of the tickets.

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Now if we wanted the exact number, we could say 42 times

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29, and we could work out the multiplication, but they

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essentially want us to be able to do it in our head.

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We want to round the numbers first and then multiply.

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So if we want to round, and really we just have two places

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here, so if we're going to round anything, it's going to

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be to the nearest ten because that's the largest place we

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have. So if we round 42 to the nearest ten-- we've done this

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drill many times-- 2 in the ones place is the less than 5,

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so we're going to round down.

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The nearest ten is 40.

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We're going to round down to 40.

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29, if we round to the nearest ten, 9 in the ones place is

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greater than or equal to 5, so we round up.

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The nearest ten is 30.

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And another way to think about it.

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Just say, well, you know, 42, that's pretty close to 40.

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29 is pretty close to 30.

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Those are literally the nearest multiples of ten that

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I can figure out, so now I can multiply.

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And here, once again, we can use-- you could call it a

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trick, but hopefully, you understand why it works.

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But 30 times 40, instead of you saying, well, this is

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going to be the same thing as 3 times 4, but we're going to

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put two zeroes at the end of it.

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30 times 40 is the same thing as 3 times 4 with two zeroes,

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so let's do that.

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So you have 3 times 4 is 12, which we know, and then we

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have two zeroes.

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We got that zero, so let's stick that zero there, and

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then we got that blue zero there, so let's

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put that over there.

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So they're going to have roughly $1,200 taken it from

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sales of the tickets.

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That is our estimate.

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