ShmoopTube

00:02

And here's a shmoopy question for your brain.

00:05

Which of the following is the best estimate of 3.05 times 7.95 minus 4… squared?

00:12

And here are the potential answers…

00:17

So, where do we start?

00:19

The first thing we notice is that the problem asks us for an estimate, not an exact answer.

00:24

So, we don’t have to multiply 3.05 by 7.95…

00:29

…we just have to find something close to that product.

00:32

To do that, we can use rounding.

00:35

Turns out, 3.05 is pretty close to 3, and 7.95 is pretty close to 8.

00:42

So instead of the quantity 3.05 times 7.95 minus 4 squared...

00:47

…we have the quantity 3 times 8 minus 4 squared, which is a lot simpler.

00:51

To get our answer, all we have to do is multiply everything out, following PEMDAS.

00:56

We do everything inside the square parentheses first,

00:59

and multiply 3 and 8 before subtracting 4.

01:03

3 times 8 is 24, and 24 minus 4 is 20.

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Then we square that, giving us 20 squared equals 400.

01:11

The answer is B.

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