trthebees 271 Posted August 11, 2019 Share Posted August 11, 2019 (WaLa² +WbLb²)÷8Z(La+Lb) The above is a typical stress calculation. I would just know that it means (WaLa² +WbLb²) ________________ 8Z(La+Lb) (Sorry, can't figure how to narrow the gap between the denominator and numerator, unless it does it when I submit this reply) Link to post Share on other sites
SkyMan 23,708 Posted August 11, 2019 Share Posted August 11, 2019 1 hour ago, Woolf said: Good explanation why it is 16: https://mindyourdecisions.com/blog/2019/07/31/what-is-8-÷-22-2-the-correct-answer-explained/ Well, we do have some old folks on here but I had no idea. From the link...... Quote Some people have a different interpretation. And while it’s not the correct answer today, it would have been regarded as the correct answer 100 years ago. Some people may have learned this other interpretation more recently too, but this is not the way calculators would evaluate the expression today. The other result of 1 Suppose it was 1917 and you saw 8÷2(4) in a textbook. What would you think the author was trying to write? Historically the symbol ÷ was used to mean you should divide by the entire product on the right of the symbol (see longer explanation below). Under that interpretation: 8÷2(4) = 8÷(2(4)) (Important: this is outdated usage!) Link to post Share on other sites
rfm010 3,521 Posted August 11, 2019 Share Posted August 11, 2019 1. Was always the answer, always will be. Numerator is 8. Denominator is 8. Business about doing 8/2 then multiplying by 4 is putting 4 in the numerator where it doesnt belong. That would be like 8/2/4. Been passing a lot of bridge construction in michigan kentucky indiana and last and least ohio. Hope the engineers are getting their math from the internet. 2 Link to post Share on other sites
Administrator +Salty Dog 69,048 Posted August 11, 2019 Administrator Share Posted August 11, 2019 On 8/9/2019 at 7:21 AM, Bama said: Now technically, even though the internet is torn, the correct answer is 16. BUT before you @ me, hear me out: say the equation was 8 / 2 x 4, thus eliminating the parenthesis component completely. You would always work from left to right, which would give you the answer of 16 (8 divided by 2 is 4, times 4 is 16). 1 Link to post Share on other sites
SkyMan 23,708 Posted August 12, 2019 Share Posted August 12, 2019 9 hours ago, rfm010 said: 1. Was always the answer, always will be. Numerator is 8. Denominator is 8. Business about doing 8/2 then multiplying by 4 is putting 4 in the numerator where it doesnt belong. That would be like 8/2/4. Been passing a lot of bridge construction in michigan kentucky indiana and last and least ohio. Hope the engineers are getting their math from the internet. Even though the answer is 16, I'm sure you don't have to worry about any engineers having to solve this kind of BS. As I said before, this is the product of some math teacher trying to trip up their students on some test to see if they can follow all the rules verbatim but this type of setup would never come up in real calculations without the writer of the equation knowing which order he wanted the operations done and writing it so it would be correct for anyone reading it. 9 hours ago, rfm010 said: That would be like 8/2/4. No because the answer to that would be 1. It would be like writing 8/2*4 = 16 perhaps it would be easier if it were written 8/2 * 4 =16? If you did want 8/2/4 then typically one of the division lines is shown longer to indicate the main division operation. However, in the absence of that, left to right prevails. Link to post Share on other sites
Jawny 4,617 Posted August 12, 2019 Share Posted August 12, 2019 https://en.wikipedia.org/wiki/Order_of_operations A google search regarding the origin of PEMDAS can be enlightening. Seems the concept goes back to mid 1600s. I recall a (perhaps incorrectly) that google was searching for employees and had a billboard with a similar mathematical question. The text was something like..."If you can solve this, you may want to work for us". Link to post Share on other sites
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