Hilfe...

[Spielerin]

.. ich kann nicht mehr rechnen..
In dem Turnier 3197 hat mein Gegner LeoNL bei Zug Nr. 2 (weiß) folgendes gelegt:5+9:3=8
Ich rechne hin und her und komme aber beim besten Willen nicht auf das Eregbnis 8. Wird ja schon stimmen, sonst hätte es ja der kluge PC nicht angenommen. Wer löst mir bitte das mathematische Rätsel??
Danke im voaus an die klugen Köpfe

Christine

[dialexna]

Hi, Punkt vor Strich:
5+(9:3)=5+3=8

[Spielerin]

stimmt.. da war mal was in der Mathestunde... während ich mir die Nägel lackiert habe, die Wimpern getuscht, die bravo gelesen und Dr. Sommer befragt habe..
Christine

[msss]

Why is 9:2×9=2 not possible?
It should be the same as 9×2:9=2

[charlotteh]

9:2x9=40.5 not 2.
Not the same as 9x2:9
I guess you mean 2:9x9=2?

[msss]

Oh haha

[FriedaBirke]

stimmt.. da war mal was in der Mathestunde... während ich (...)die bravo gelesen und Dr. Sommer befragt habe..

Dr Sommer hat aber nicht über Mathe aufgeklärt Keine Ahnung, um welches Spiel es geht, aber wenn man die Zahlen verdreht passt es doch. Also anstatt 5+9:3=8.... 9:3 + 5 = 8 nach Adam Riese.

Gruß Frieda

[Erna]

9:2x9=40.5 not 2.
Not the same as 9x2:9
I guess you mean 2:9x9=2?

She probably means the old official rule; "x" goes before ":"? But that would give 9:(2x9)= 0.5, also incorrect.
Here they apply it up to date, x and : are 'equal', and + and - are 'equal' But x and : always go before + and -, by the following rule
"Multiplication and division precede addition and subtraction. When two operators have the same precedence, then work from the left to right.".

With the rules here; 9:2x9= 40.5, old school 0.5
With the rules here; 9x2:9=2, old school too 2
With the rules here; 2:9x9=2, old school 0.025

Edit:
BTW, this oldschool rule has been changed around 1992, so everybody who left school (or math) before this date would come to 0.5, and apply old school style. Nobody told us....

[Statler]

Just out of personal curiosity:

@erna: for which country do you state the change from right-associated (not sure if that is what you call this convention in English) to left-associated convention? Afaik for at least (parts of) Austria it has always (or at least back until 70s) been left-associated.

However, my latest info is that there is still no official global agreement on this issue and that majorty is using left-associated and all claim that this issue can and should be prevented by using parantheses (which is obviously not helping us here for Summy).

Edit: thanks, answers my questions - unless someone can provide info about a global conventiin. Left/right means if a/b/c means (a/b)/c (=left) or a/(b/c) (=right).

[Erna]

@Statler;
I am dutch.
Up to my last exams in 1991 we had to use the rule that multiplying comes before deviding as long as they were in one sentence. After that year I had nothing to do with mathematics anymore, so I am not sure. But it seems the rules have been changed for some reason.
And to be honest, I have no clue what right/left-association means...

[Mathomo]

9:2*9=2 should work. Internally the computer calculates with decimal values and rounds only at the end.

According to the rules the term is calculated from left to right. But this is irrelevant in this case.

I assume that something else hindered the validity of the term 9:2*9=2.
@msss: Could you please show the context of your term? A screenshot would be nice.

[charlotteh]

9:2*9=2 should work. Internally the computer calculates with decimal values and rounds only at the end.

According to the rules the term is calculated from left to right. But this is irrelevant in this case.

I assume that something else hindered the validity of the term 9:2*9=2.
@msss: Could you please show the context of your term? A screenshot would be nice.

9:2*9=2 werkt niet omdat het 40,5 is en niet 2. Want 9:2=4,5 en als je dat vermenigvuldigt met 9 kom je op 40,5.
2:9*9=2 zou wel moeten werken.

[Mathomo]

You are right . Sometimes the obvious is too obvious .

[charlotteh]

You are right . Sometimes the obvious is too obvious .