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Introduction to PEMDAS 6557 Views


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Description:

Please Excuse My Dear Aunt Sally. What did she do? Slander the process of order of operations?

Language:
English Language
Common Core Standards:

Transcript

00:02

In life, order matters. If we didn't pay heed to the natural order

00:06

of things, we'd wear our socks over our shoes.

00:09

There would be more fist fights than normal at the DMV.

00:11

And we'd shower after getting dressed. Algebra is no different. There is a right

00:16

and wrong way to do things, and a proper order in which to do them.

00:20

To remember what that order is, we use an acronym called PEMDAS.

00:24

It stands for: parentheses, exponents,

00:27

multiplication and division, and addition and subtraction.

00:32

It does NOT stand for Private Eye Makes District Attorney Sad. But if it helps you remember

00:37

the acronym, more power to you. Let's see it in action.

00:41

Take the problem 5 - 3 + 6 / 2 + (7 -5) in parentheses - squared.

00:50

According to PEMDAS, first we have to take care of those pesky parentheses.

00:53

Easy enough. 7 - 5 isn't rocket science. Good thing, or there would be far too many

00:59

rocket scientists flooding the job market.

01:02

If we rewrite our problem, we get:

01:04

5 - 3 + 6 / 2 + 2 squared.

01:09

Next we have to rub out any exponents. That fella on the end is the only exponent, so

01:14

let's actually square 2 and send him on his way.

01:17

Now we've got 5 - 3 + 6 / 2 + 4

01:22

There's no multiplication, but we do have a tiny bit of division to perform. 6 / 2

01:27

gets our attention first, so says PEMDAS. Yeah, we pretty much do whatever it tells

01:32

us to do. We're whipped.

01:34

We can rewrite our problem as 5 - 3 + 3 + 4

01:39

Addition and subtraction hold equal weight. Subtraction was on the Special K diet for

01:43

the past couple of weeks but it didn't take, so we can just perform all remaining operations

01:48

from left to right to give us our final answer : 9

01:50

Quite a bit different from the answer we'd get if we did everything from left to right

01:54

with disregard for procedure. Here, different is not good.

01:59

No matter how stylin' you think you look in your shoe-socks.

02:02

So there's PEMDAS in a nutshell. Live it. Breathe it. Shmoop it. Love it. Bye.

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