Vladimir M. Klochko wrote:

> Furthermore, it's possible to use the same method to divide by 5:
>     1/5=0.0011001100110011...

  Which is of course quite useful in decimal conversion.

> Are these methods (quick and not exact) usefull?
> May be. I have a doubt.

  You misunderstand something here.  They *are* quick, and they *are*
exact.  They are the fastest way to perform constant divisions.  They
are *as* accurate as but much faster than "long division" algorithms.
In either case, you must perform *all* intermediate calculation without
truncation, that is, you have to retain and perform addition on the
*whole* of any right-shifted value.

  As with long division, adding half the divisor to the dividend before
the division is the easiest way to perform rounding, i.e., add 1 if
dividing by three, add 2 if dividing by 5 and so on.

  Cheers,
        Paul B.