On Thu, 2004-10-28 at 04:23, Mark Hubbart wrote: > Reconfigure your misconceptions: decimal numeric notation has no basis > in reality. It is simply a way for humans to write down numbers. > Decimal, like binary, is a notation, a way to represent finite > numbers. It can not represent all finite numbers satisfactorily, > though; the notation has it's failings. One of the failings is shown > when representing finite rational numbers where the denominator is not > solely a multiple of powers of 2 and 5 (the factors of ten). > > 1/5 => 0.2 > 1/2 => 0.5 > 1/4 => 0.25 > 1/7 => 0.142857142857143.... (whoops) Another funny failing of the notation is that not everything that looks like a number actually represents a number. The following is quite intriging: x = 0.99999... (infinite serie of 9s) 10*x = 9.99999... 10*x - x = 9*x = 9 So x = 1! IIRC, any 'word' that ends with an infinite serie of 9s does not represent an actual real number. Guillaume.