Order of Operations

[notbatman]

Somebody (reddit) has tried to convince me that the order of operations has been inverted and is now right --> left except within parentheses.

...

Example:

a = 7 + 3^2 * (10 / 2)

a = 7 + 3^2 * 5

a = 7 + 9 * 5

a = 7 + 45

a = 52

...

When do we start counting the alphabet starting with Z?


fake edit:

I asked Google and it says 7 + 9 * 5 = 52. What compiler does Google use?



real edit:

So basically (7 + 9) * 5 ≠ 7 + 9 * 5.



edit 2:

Tell me a single benefit of having sign precedence? Why is it suddenly in use? The vector is entering form a non-zero point, how does this intrusive rule do anything but add unneeded complexity which equates to additional energy expenditure adding unneeded order? It takes less energy to get 80 than it does to get 52.



edit 3:

I must protest this delay in calculation, signs don't weight nothing!



edit 4:

Lets see if I can simplify this,



7 + 9 * 5

correct:

   "What is seven plus nine times five?" = 80

new backwards inefficient sign style with useless calculation:

   "What is nine times five plus seven?" = 52

The order is A, B, C, ..., this is a fixed value it never changes and if it does then it's wrong; the dog chewed on it and the saliva caused a short circuit and it corrupted the computer memory and the dogs owner who wrote the software forgot to add a CRC check. The alphabet does not start at B, the same with numbers; you don't start counting at 2!





edit 5:

I drew a picture to illustrate the problem:

[Foxpup]

TLDR: ITT, notbatman fails fifth grade arithmetic.

[notbatman]

^^^ Not it's not a fail because the current rule is #1 useless and #2 adds an extra step, possibly two thus increasing the energy required to calculate. You have to weigh the operators and possibly make a jump before you mash your numbers together instead of just starting with the leftmost number every time.

Give me one reason [the logic] for why multiplication should be given precedence over starting the calculation with the leftmost number? Why is multiplication greater than addition or division; all operators weigh zero, only numbers have weight. The operators have to be defined as complex numbers, you can't have hidden definitions.

[Ciscopro2000]

PEMDAS

In cases like these, we follow the order of operations. The order in which operations should be done is abbreviated as PEMDAS:
1. Parentheses
2. Exponents
3. Multiplication and Division (from left to right)
4. Addition and Subtraction (from left to right)

[bivaetjetakoe]

Math lessons from notbatman

[notbatman]

Instances of PEMDAS searches on YouTube are ZERO before August 2008. What is this garbage?

Sauce:

https://trends.google.com/trends/explore?date=all_2008&geo=US&gprop=youtube&q=PEMDAS


What about XOR, where does this operation fit into the hierarchy, is it more important than addition?

7 + 9 ⊕ 5 = x.

Does x = 19, or x = 21?

[odolvlobo]

Personally, I prefer

ax²+bx+c

to

a(x²)+(bx)+c

and similarly

a₀+a₁x+a₂x²+a₃x³+...+a_nxⁿ

to

a₀+(a₁x)+(a₂(x²))+(a₃(x³))+...+(a_n(xⁿ))

[notbatman]

7 + 9 * 5 = 80



God hates fags.

[SaltySpitoon]

Whoever told you on Reddit that order of operation is now right to left is incorrect. It is still the same as always, left to right with parentheses > exponents > multiplication/division > addition/subtraction taking precedence in that order.

7+9 *5 is 52

write it out in two steps, 7+9  and then * 5 is the same notation as (7+9) * 5 which as you pointed out is 80. These are just arbitrary conventions set a long time ago so that everyone would read math the same way.

[notbatman]

^^^ Solar powered calculator says the answer to 7 + 9 * 5 is 80. This useless convention that does nothing but add unneeded complexity to calculations must have been implemented not so long ago...

Why oh why would a useless and unneeded convention that prioritizes multiplication (the star) over addition (the cross) be implemented? Who could be behind this seemingly recent change?





How about you get pet your cat in wrong direction for a little while, see what kind of reaction you get.

[BADecker]

^^^ It depends on what reaction you are looking for. If you don't get the reaction you want, you are doing it the wrong way.

As SaltySpitoon says above, it all has to do with the general understanding, so that we are all on the same page.

[odolvlobo]

^^^ Solar powered calculator says the answer to 7 + 9 * 5 is 80. This useless convention that does nothing but add unneeded complexity to calculations must have been implemented not so long ago...

Why oh why would a useless and unneeded convention that prioritizes multiplication (the star) over addition (the cross) be implemented? Who could be behind this seemingly recent change?

Recent? Maybe for you.

The rule specifying the order of multiplication and addition is hundreds of years old.

Here is some information: http://mathforum.org/library/drmath/view/52582.html

[notbatman]

^^^ Solar powered calculator says the answer to 7 + 9 * 5 is 80. This useless convention that does nothing but add unneeded complexity to calculations must have been implemented not so long ago...

Why oh why would a useless and unneeded convention that prioritizes multiplication (the star) over addition (the cross) be implemented? Who could be behind this seemingly recent change?

Recent? Maybe for you.

The rule specifying the order of multiplication and addition is hundreds of years old.

Here is some information: http://mathforum.org/library/drmath/view/52582.html

History of Order of Operations

Date: 11/22/2000 at 10:56:37
From: Brian Huffine
Subject: History of Order of Operations

I was teaching a computer class and the history of order of operations
came up. Where, when and with whom did the order of operations first
originate? ...

Date: 11/22/2000 at 12:12:26
From: Doctor Peterson
Subject: Re: History of Order of Operations

Hi, Brian.
...

I spent some time researching this question, because it is asked
frequently, but I have not found a definitive answer yet. ...

edit:

Oh, there more in the links Doctor Peterson provides:

More on Order of Operations


Date: 02/13/2000 at 13:59:53
From: Jerome Breitenbach
Subject: Order of Arithmetic Operations

Hi,

I'm a professor in the field of electrical engineering. Occasionally I
remind my students of the precedence order regarding the four
arithmetic operations: addition, subtraction, multiplication, and
division. Apparently though, based upon viewing numerous Web sites and
the messages of various on-line discussion groups, there seems to be
some controversy regarding these simple rules! ...

... my search for an "authority" on this matter has been nearly
fruitless. ...