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If 1/3 x 3 = 1....

...and 1/3 = 0.333333333..

Why is it that 3 x 0.333333.. will never be equal to 1 no matter how many decimal places you use?
«1

Comments

  • Sonicstud85
    Sonicstud85 Posts: 2,161
    because it is what it is
  • Friend Or Defoe
    Friend Or Defoe Posts: 18,091
    edited June 2015
    0.9 occurring is defined as 1.

    It's one of Zeno's paradoxes.
  • Talal
    Talal Posts: 11,490
    To make life easier
  • sillav nitram
    sillav nitram Posts: 10,164
    don't worry your pretty little head over it.
  • Callumcafc
    Callumcafc Posts: 63,766
    x = 0.99999999...

    0.99999999... x 10 = 9.99999999...
    therefore 10x = 9.99999999...

    10x - x = 9x
    9.99999999.... - 0.99999999.... = 9

    therefore 9x = 9 and x=1

    so 0.99999999... = 1
  • Red_in_SE8
    Red_in_SE8 Posts: 5,961

    x = 0.99999999...

    0.99999999... x 10 = 9.99999999...
    therefore 10x = 9.99999999...

    10x - x = 9x
    9.99999999.... - 0.99999999.... = 9

    therefore 9x = 9 and x=1

    so 0.99999999... = 1

    That seems like a flawless answer. I will have to ponder over it tonight when I have time.
  • dizzee
    dizzee Posts: 5,616
    Is this charltonlife?
  • smudge7946
    smudge7946 Posts: 4,131
    Why is it that when you take something by ship it's called a cargo
    When you take something by car it's called a shipment
  • PL54
    PL54 Posts: 10,757
    Obviously infinity is never reached

    Absolute zero doesn't exist either, just approximations to it which are called 0
  • If it aint oo or o now it's 0.000000 what the feck do you lot do during your down time , there must be things more interesting to do
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  • If it aint oo or o now it's 0.000000 what the feck do you lot do during your down time , there must be things more interesting to do

    Train spotting?

  • Uboat
    Uboat Posts: 12,195
    When someone asks you to justify something mathematical, just say 'bidmas' then walk away.
  • PL54
    PL54 Posts: 10,757

    If it aint oo or o now it's 0.000000 what the feck do you lot do during your down time

    I'm a body double for Stephen Hawking
  • I am one for buster blood vessel
  • Fiiish
    Fiiish Posts: 7,998
    It is purely an idiosyncrasy of the decimal or base 10 system we use. 0.333... is simply a decimal representation of the expression "a third of one whole" and is meaningless without understanding that this is what it means.

    If we use Base 12, then 0.333... is expressed simply as 0.4, therefore 0.4*2 is 0.8 and 0.4*3 is 1.

    We likely use Base 10 as standard because we have 10 digits across both hands, so if we were born with 5 fingers and 1 thumb (or if Norfolk was the birthplace of mathematics) then we would probably be using Base 12 as standard and we would not have this conundrum (although there would likely be a similar conundrum if we used Base 12 instead).
  • cafcnick1992
    cafcnick1992 Posts: 7,413
    PL54 said:

    Obviously infinity is never reached

    Absolute zero doesn't exist either, just approximations to it which are called 0

    How about Rezas average performances on the player rating threads?

    Surely that was absolutely zero?
  • cabbles
    cabbles Posts: 15,256
    What about Graham's number? I started watching an Horizon programme on bbc 4 the other day about the number infinity. It mentioned google plexi and the fact that google plex was the highest number you can get but then this Graham's number (the actual number he doesn't know how to represent in digits, he does know that it ends in 7 I think), is all about the depth and dimension of a cube. If I was following the programme correctly.

    Basically when we get to number of that size, our brains need to pass it on to computers because we do not possess the capacity or memory to calculate such vast amounts - again it comes back to scale. in the same way we cannot comprehend the planck length or the enormity of the universe. We are of a certain size and anything whether it be a number or our surroundings is only relative in our minds to the size we are
  • cabbles
    cabbles Posts: 15,256
    https://en.wikipedia.org/?title=Graham's_number

    Just take a look at the Wikipedia page for God's sake. If you have a brain for this then I envy you. I would love to put into context the theory behind this and astro/particle physics
  • Friend Or Defoe
    Friend Or Defoe Posts: 18,091
    PL54 said:

    Obviously infinity is never reached

    Absolute zero doesn't exist either, just approximations to it which are called 0

    Infinity isn't a number and absolute zero is the lowest possible temperature, nothing to do at maths and it does exist.
  • Fiiish
    Fiiish Posts: 7,998

    PL54 said:

    Obviously infinity is never reached

    Absolute zero doesn't exist either, just approximations to it which are called 0

    Infinity isn't a number and absolute zero is the lowest possible temperature, nothing to do at maths and it does exist.
    Absolute zero is more to do with physics/chemistry. If you consider temperature as a measure of thermal motion, then Absolute Zero is the point where no thermal motion takes place.

    I think people get confused about it not existing as it is pretty much impossible to detect anything at absolute zero, since to measure thermal activity actually requires a tiny degree of thermal activity to take place (the mere introduction of measuring apparatus to an environment that could potentially be absolute zero will cause the thermal activity to rise). Basically it is like being asked to look at something without using light - you know it is there but you are unable to observe it unless some measure of light is hitting your eyes from the object then you cannot perceive it (at least not without equipment).

    cabbles - I love Graham's Number. The simple reason for its fame is the fact that it is the largest number ever used in a mathematical proof. It is so large it can never be graphically represented in its entirety in this universe (at least that is what I have read). I mean anyone could come up with a meaningless, really big number but it is actually a number that has a purpose.
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  • lolwray
    lolwray Posts: 4,902
    my anoraks in the dry cleaners at the moment ...............
  • Greenie
    Greenie Posts: 9,172
    This is the leading candidate for 'Bore of the year thread'.
  • Friend Or Defoe
    Friend Or Defoe Posts: 18,091
    If there are some insomniacs a reckon myself and fiiish could cure them! ;-)
  • cabbles
    cabbles Posts: 15,256
    Fiiish said:

    PL54 said:

    Obviously infinity is never reached

    Absolute zero doesn't exist either, just approximations to it which are called 0

    Infinity isn't a number and absolute zero is the lowest possible temperature, nothing to do at maths and it does exist.
    Absolute zero is more to do with physics/chemistry. If you consider temperature as a measure of thermal motion, then Absolute Zero is the point where no thermal motion takes place.

    I think people get confused about it not existing as it is pretty much impossible to detect anything at absolute zero, since to measure thermal activity actually requires a tiny degree of thermal activity to take place (the mere introduction of measuring apparatus to an environment that could potentially be absolute zero will cause the thermal activity to rise). Basically it is like being asked to look at something without using light - you know it is there but you are unable to observe it unless some measure of light is hitting your eyes from the object then you cannot perceive it (at least not without equipment).

    cabbles - I love Graham's Number. The simple reason for its fame is the fact that it is the largest number ever used in a mathematical proof. It is so large it can never be graphically represented in its entirety in this universe (at least that is what I have read). I mean anyone could come up with a meaningless, really big number but it is actually a number that has a purpose.
    It is a testament to the human brain. Like I say, I would give anything to be of that intelligence or, rather have a mind that gets maths/science. Imagine working in somewhere like the Perimeter Institute for Theoretical Physics, must be amazing
  • bobmunro
    bobmunro Posts: 20,846
    edited June 2015
    Graham's number isn't infinity - it doesn't even approach infinity - because infinity isn't a number, it's an imaginary mathematical construct. Infinity can be represented as one divided by zero (any number divided by zero in fact) - zero isn't a number, again a mathematical construct - so it would follow that infinity cannot be a number.

    No different to the square root of -1 also being imaginary (i) but comes in pretty damn useful for example when solving certain quadratic equations!!

    Anyway - move on - RD out and all that!

    P.S. Negative Kelvin temperatures (below 0 degrees Kelvin) have been detected using ultracold atoms!
  • Friend Or Defoe
    Friend Or Defoe Posts: 18,091
    bobmunro said:

    Graham's number isn't infinity - it doesn't even approach infinity - because infinity isn't a number, it's an imaginary mathematical construct. Infinity can be represented as one divided by zero (any number divided by zero in fact) - zero isn't a number, again a mathematical construct - so it would follow that infinity cannot be a number.

    No different to the square root of -1 also being imaginary (i) but comes in pretty damn useful for example when solving certain quadratic equations!!

    Anyway - move on - RD out and all that!

    Nearly.

    You can't divide anything by zero, but 1/x tends to infinite as x tends to 0. It's represented by a sideways 8 and zero is a number. How many penguins play for Charlton?

  • cabbles
    cabbles Posts: 15,256
    bobmunro said:

    Graham's number isn't infinity - it doesn't even approach infinity - because infinity isn't a number, it's an imaginary mathematical construct. Infinity can be represented as one divided by zero (any number divided by zero in fact) - zero isn't a number, again a mathematical construct - so it would follow that infinity cannot be a number.

    No different to the square root of -1 also being imaginary (i) but comes in pretty damn useful for example when solving certain quadratic equations!!

    Anyway - move on - RD out and all that!

    P.S. Negative Kelvin temperatures (below 0 degrees Kelvin) have been detected using ultracold atoms!

    I was watching a programme about infinity that mentioned/referenced Graham's number. It will be on the I-Player, worth a look if you like this sort of thing.
  • rikofold
    rikofold Posts: 4,051

    x = 0.99999999...

    0.99999999... x 10 = 9.99999999...
    therefore 10x = 9.99999999...

    10x - x = 9x
    9.99999999.... - 0.99999999.... = 9

    therefore 9x = 9 and x=1

    so 0.99999999... = 1

    This only works because 0.999... is treated as an absolute number in that proof. The flaw is that it isn't an absolute number, and whilst you might want to rationalise 10x-x = 9x in that way it isn't actually true because x isn't an absolute. It's fairly obvious that whilst the more 9s you have the closer it is to 1 it will never actually be 1.

    However, I'm pretty sure that anyone seeing 0.999... will treat it as 1 because it's as near as any number could be. So who cares really.
  • MrOneLung
    MrOneLung Posts: 26,856

    If there are some insomniacs a reckon myself and fiiish could cure them! ;-)

    Not just on this thread either ......
  • bobmunro
    bobmunro Posts: 20,846

    bobmunro said:

    Graham's number isn't infinity - it doesn't even approach infinity - because infinity isn't a number, it's an imaginary mathematical construct. Infinity can be represented as one divided by zero (any number divided by zero in fact) - zero isn't a number, again a mathematical construct - so it would follow that infinity cannot be a number.

    No different to the square root of -1 also being imaginary (i) but comes in pretty damn useful for example when solving certain quadratic equations!!

    Anyway - move on - RD out and all that!

    Nearly.

    You can't divide anything by zero, but 1/x tends to infinite as x tends to 0. It's represented by a sideways 8 and zero is a number. How many penguins play for Charlton?

    I understood zero was invented by the Babylonians as a tipping point from positive to negative. I can accept your point that zero is a number - but it's even!