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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.