Post me your hardest maths question you know

fez said:
Maybe thats the problem. We are looking at it from different viewpoints. As with most fields, they have their accepted truths that do not necessarily make sense outside of that field.
Click to expand...

But maths is not just a self-contained field in that sense. Arguably there is no "outside" of maths; everything must obey it (as long as you accept its axioms, which any sane person does).

fez said:
The way I see things like this is that the more precision you get, the less value each new unit of precision has. So if you have an infinite number of 9's after the point that you will always be getting closer and closer to 1.0r but you will never truly hit it. You would get to the point where the two were indistinguishable from each other but they would never truly be identical in value.
Click to expand...

Mathematically, a convergent infinite series (of which an example is 0.9r) is equal to the value to which it converges.

Since the whole debate is mathematical in nature, and 0.9r and 1 are mathematical entities, there is only one answer, and that is the one that arises from the axioms of mathematics.

It doesn't make sense to discuss this outside the context of maths!

fez said:
I was always taught that when we use recurring numbers that we are dealing in approximations rather than a precise value. I think that is where I am having the trouble.
Click to expand...

Well whoever told you that was wrong :) It's certainly a cumbersome notation, which is why it's always preferable to write 1/3 rather than 0.3r, but their meanings are identical, in the same way that the meanings of 0.9r and 1 are identical.

Of course, if you write down a finite truncation of a recurring decimal expansion, then yes, it's an approximation.
 
Last edited:
meghatronic said:
Everyone should bloody know that!
Click to expand...

You have to do further maths AS level to find out that sqrt(-1) = i nowadays.




I don't really know any really hard problems, but sort of mathsy thing to solve:

Resistance between two vertices of a cube directly opposite each other, when each edge is a 1 Ohm resistor.

1/R = 1/R1 + 1/R2, and R=R1+R2 Helpful.



Also, fun:

sqrt(-1/64) last night!
 
Last edited:
Radiation said:
Because it's not being honest and misses a pretty important issue, the calculation itself, you can come up with any old calculation but just because you write it down doesn't mean you're magically given the answer, it takes work to do calculations.

If we wanted to calculate it we either need infinite time or an infinitely powerful computer, considering we don't have either the calculation will never be done and couldn't anyway because it deals with infinity.
Click to expand...

BY this logic sqrt(2) * sqrt(2) != 2
because you can't write down the infinite digits after the decimal point. However, ever one else on the planet who did maths past the age of 12 knows that sqrt(2) * sqrt(2) = 2 by definition.


Pi has an infinite number of digits after the decimal, i..e it is an irrational number, yet it is easy to right down the symbol and manipulate equations with it. e.g. we can define the function sin(pi) , yet you seem to think this is impossible because you can't write down all the digits of pi on a bit of paper.

I don't like to insult people, but in this case I can make a general statement that is true. If anyone doesn't believe that 0.9r = 1 then they are simply not smart enough to get the
concept. This isn't a problem, in every day life you don't need to know such things, but you just have to except you are not smart enough to understand why this is the case.
I'm not saying such people are stupid, just not understanding of the basics of maths. The wikipedia article has a nice section discussing various reasons why some young students don't understand.
 
Inquisitor said:
Well whoever told you that was wrong :) It's certainly a cumbersome notation, which is why it's always preferable to write 1/3 rather than 0.3r, but their meanings are identical, in the same way that the meanings of 0.9r and 1 are identical.

Of course, if you write down a finite truncation of a recurring decimal expansion, then yes, it's an approximation.
Click to expand...

There we go, sorted! Thats where I couldnt reconcile the two! If you take 1/3 to be the same as 0.3r then yeah 0.9r = 1.

Im still not down with the 0.9r = 1 if the r represents an infinite repetition of the 9. If we take 0.3r to be the exact and same as 1/3 then we are gravy.
 
fez said:
Just have to remember that its only £25 paid. The fact that the 3 chaps have paid £9 each just means that you can see where the £2 tip has come from.

Paid £30 thinking that was right.
Discount takes their total to £25 meaning £5 to give back to 3 people.
Dodgy waiter decided that you would end up with all sorts of trouble doing this so pockets 2 quid out of the 5 and gives the 3 chaps £1 each.

You are no longer looking at a total of £30 having been contributed to the bill but £27. Seeing as the till only wants £25, there is 2 left for the light fingered parisian.
Click to expand...

How much did the men pay? £30
How much change did they recieve? £3.

Therefore they paid £27 for the meal, not £25.

£27+£2 the waiter kept = £29.:D
 
2edwl1x.png
 
w3bbo said:
How much did the men pay? £30
How much change did they recieve? £3.

Therefore they paid £27 for the meal, not £25.

£27+£2 the waiter kept = £29.:D
Click to expand...

Why do you keep repeating this with your +£2 nonsense? Are you just trying to give someone a seizure through sheer frustration? :p
 
As I was going to St Ives
I met a man with seven wives
Each wife had seven sacks
Each sack had seven cats
Each cat had seven kits
Kits, cats, sacks, wives
How many were going to St Ives?
 
You must log in or register to reply here.
Back
Top Bottom