8 / 2 (2 + 2) =

Some hospitals will weigh you in kilograms.
And going back to the original (sarcastic) comment, your weight on the moon will be six times less than on earth, but your mass will stay the same.
 
Nothing wrong with expressing material quantities in units of mass, in fact it's probably technically more accurate since it doesn't change with gravity. As long as you understand the difference between weight and mass.

I was going through a 172R manual, and in the weight and balance section, they give tables in both English and SI units. In the SI unit flight envelope table, the moment is given in kilogram meters. If one of my engineers ever gave me a calculation in kilogram meters, they would be fired on the spot.
 
Initial Fix said:
As shown it’s really unclear. Without brackets around the 2(2+2) it is 16. Assuming brackets it’s 1. I’ve seen this many times as an engineer where someone implies a math operation but does the math wrong anyway.
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Exactly. It doesn't have brackets or parathesis around 2(2+2). If it did have brackets it's a different question. In my opinion you cannot assume they meant to put brackets around 2(2+2). If you want the answer to be 1 the equation would be 8/(2(2+2)), but that is not what is written.
 
AV8R_87 said:
Some hospitals will weigh you in kilograms.
And going back to the original (sarcastic) comment, your weight on the moon will be six times less than on earth, but your mass will stay the same.
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But since we’re arguing about technically correct stuff, “six times less than,” say, 200 pounds would be a negative 1000 pounds. Did you mean “one sixth the weight on earth”? :devil:
 
luvflyin said:
The parentheses around 8/2 changes nothing. The answer is 16 with or without them.

The order is PEMDAS: Parentheses, Exponents, Multiplication, and Division (from left to right), Addition and Subtraction (from left to right).
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Agreed. I believe the lack of clarity results from the way it is notated. If it were written as:

8
______
2(2+2)

then the answer is obviously 1. The linear method of writing things out is where we run into issues. For instance, we write the fraction for 0.5 linearly as 1/2 even though technically it is

1
_
2
 
flyingpreacher said:
Agreed. I believe the lack of clarity results from the way it is notated. If it were written as:

8
______
2(2+2)

then the answer is obviously 1. The linear method of writing things out is where we run into issues. For instance, we write the fraction for 0.5 linearly as 1/2 even though technically it is

1
_
2
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The linear way of that is 8/(2(2+2))
 
Anyone with a computer programming background will have no problem with linear expression. Of course the OP formula won't evaluate in most languages because the multiplication operator is missing.
 
Ed Haywood said:
Anyone with a computer programming background will have no problem with linear expression. Of course the OP formula won't evaluate in most languages because the multiplication operator is missing.
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I dunno ‘bout programming because I ain’t a programmer other than playing with Basic many moons ago. But I do have a few elaborate Excel spreadsheets I’ve made. If I do sumpin like 2(blah blah) it says unable or something like that and offers up a suggestion like 2*(blah blah) will work. Don’t make no sense to me. I’d expect Excel to be smarter than that.
 
luvflyin said:
I dunno ‘bout programming because I ain’t a programmer other than playing with Basic many moons ago. But I do have a few elaborate Excel spreadsheets I’ve made. If I do sumpin like 2(blah blah) it says unable or something like that and offers up a suggestion like 2*(blah blah) will work. Don’t make no sense to me. I’d expect Excel to be smarter than that.
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as much as I dislike microcrap software, I will give excel a pass because software can't read minds.

(if it could, I'd want to use it to try to read a woman's mind)
 
Half Fast said:
So, an ERAU graduate!
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As an aside, they have a series of PPL prep videos. I am going to use one of them for a ground school segment I'm teaching in the spring on systems. The graphics are great and it really explains how an aircraft engine works.

The only problem is that they have the explanation of a carburetor venturi.... wrong.
 
flyingpreacher said:
Agreed. I believe the lack of clarity results from the way it is notated. If it were written as:

8
______
2(2+2)

then the answer is obviously 1. The linear method of writing things out is where we run into issues. For instance, we write the fraction for 0.5 linearly as 1/2 even though technically it is

1
_
2
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Eggzactly. Pretty sure Newton and Einstein didn't live under lean-tos. Why would they pick a slash when a roof was so easy to draw and clearly covered everything.
 
if you add in the correct operands the equation is 8 ÷ 2 × (2 + 2) which solves to 4 × 4 = 16

The ambiguity is the fault of the author. the addition of another parentheses or even just the explicit multiplication sign clears it all up
 
luvflyin said:
The linear way of that is 8/(2(2+2))
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Well, therein lies my point. Did the author intend for it to be the way you suggest (16), or did he merely fail to recognize that the linear inscription does not render the same as the “over-under” equation.
 
flyingpreacher said:
Well, therein lies my point. Did the author intend for it to be the way you suggest (16), or did he merely fail to recognize that the linear inscription does not render the same as the “over-under” equation.
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I’m guessing it was written very specifically, knowing that the mild omission would create tremendous conflict.
 
TCABM said:
It’s 1 and I didn’t learn order of operations 100 years ago.

That some idiot screwed up coding a calculator and threw in an extra operator isn’t my problem.

Kids and their new math.
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One. And I literally just completed high school.
 
Lachlan said:
Thank God pilots don't need to know anything about math.
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Not "When empty weight C. G. falls within range given, computation of critical fore and aft C. G. positions is unnecessary. Range is not valid for non-standard arrangements."
 
Rene said:
None.

The only people who have been to the moon used "American" measurement.
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Go read some NASA documents on the Apollo missions. You'll find out that the Apolo Guidance Computer was doing all its work in metric units.

Rene said:
One. And I literally just completed high school.
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Ask for a refund on your school tax.
 
Ed Haywood said:
Do you talk like that to kids fresh out of school in real life?
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When they have been failed by the education system? Yes. It was directed at the school system, which charged a lot of money for the education it provided, not at her.

It's might be ok for people that haven't done any serious math in 20 years to struggle with this. A fresh high school graduate? Not that ok.
Same thing I told a long time ago to an ERAU student that was interning with us. He struggled solving 3x^2+5x=12.
 
Rene said:
Not "When empty weight C. G. falls within range given, computation of critical fore and aft C. G. positions is unnecessary. Range is not valid for non-standard arrangements."
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Going back to my post #46 re. weight and balance in SI units, moments given in kilogram-meters "work" because the weight units are irrelevant as long as the numerical values are in the correct proportions. It's a classic example of the right answer for the wrong reason. It works for computing a CG location, but if you actually tried to calculate forces and stresses that way, your building would collapse and people would get killed.
 
AV8R_87 said:
When they have been failed by the education system? Yes. It was directed at the school system, which charged a lot of money for the education it provided, not at her.

It's might be ok for people that haven't done any serious math in 20 years to struggle with this. A fresh high school graduate? Not that ok.
Same thing I told a long time ago to an ERAU student that was interning with us. He struggled solving 3x^2+5x=12.
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Well, stop on here, or go away. We have discussions about why PoA is shrinking, and how to get more young folks interested in PoA and Aviation. Then an enthusiastic young pilot joins our discussion, and what's the first thing that happens? You decide to show how smart and superior you are by tearing them down. It wasn't even clever or original. Congratulations, you are the 5 millionth person on the Internet to use the school tax refund line. And you used it to insult an 18 year old. You must be proud.
 
Ed Haywood said:
Well, stop on here, or go away. We have discussions about why PoA is shrinking, and how to get more young folks interested in PoA and Aviation. Then an enthusiastic young pilot joins our discussion, and what's the first thing that happens? You decide to show how smart and superior you are by tearing them down. It wasn't even clever or original. Congratulations, you are the 5 millionth person on the Internet to use the school tax refund line. And you used it to insult an 18 year old. You must be proud.
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Here's her problem right here:
Rene said:
Having literally just escaped from high school, I don't have a very high opinion of what passes for an education system in this country. IMHO, teaching is an afterthought, if it is thought of at all, in a social experiment to convince everybody that they can do anything without any sort of training whatsoever. (Absurdly, while not permitting anyone to actually do anything at all.)
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Any education is what one makes of it.
 
pfarber said:
if you add in the correct operands the equation is 8 ÷ 2 × (2 + 2) which solves to 4 × 4 = 16

The ambiguity is the fault of the author. the addition of another parentheses or even just the explicit multiplication sign clears it all up
Click to expand...
I, and every other student at my school who was paying attention, was taught "PEMDAS" as the order of mathematical operations.
In the example, there are no exponents, or subtraction operations.
So: For 8/2(2+2)
Parenthesis: 8/2(4)
Multiplication: 8/8
Division: 1
 
Rene said:
I, and every other student at my school who was paying attention, was taught "PEMDAS" as the order of mathematical operations.
In the example, there are no exponents, or subtraction operations.
So: For 8/2(2+2)
Parenthesis: 8/2(4)
Multiplication: 8/8
Division: 1
Click to expand...
How does division fit into the order of operations? Does it have a higher, lower, or equivalent precedence than multiplication?
 
Unfortunately there are different “schools of thought” in many thing with numbers that cause confusion. Even something as simple as dates. For example I would read the date 3/8/24 as march 8th 2024, but many other countries would read it as august 3rd 2024. ( I have seen this exact thing cause major delays in a large processing plant construction project when sub assemblies were made in europe for a Plant constructed in the usa).
 
Rene said:
I, and every other student at my school who was paying attention, was taught "PEMDAS" as the order of mathematical operations.
In the example, there are no exponents, or subtraction operations.
So: For 8/2(2+2)
Parenthesis: 8/2(4)
Multiplication: 8/8
Division: 1
Click to expand...
Equations are left to right with PEMDAS applied. So:
Parenthesis 8/2(4)
MD (Multiplication/Division - Left to right) 4(4)
Result 16

Mathematics is not open to interpretation. Writing a mathematic equation is a recipe for confusion and resulting mis-interpretation.
 
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