division by 7 efficiently ???

[Paul Rubin]

"Krypto" <krypto.wizard at gmail.com> writes:

> The correct answer as told to me by a person is
> 
> (N>>3) + ((N-7*(N>>3))>>3)
> 
> 
> The above term always gives division by 7

Well, not exactly:

    [GCC 3.4.2 20041017 (Red Hat 3.4.2-6.fc3)] on linux2
    Type "help", "copyright", "credits" or "license" for more information.
    >>> def f(N): return (N>>3) + ((N-7*(N>>3))>>3)
    ... 
    >>> f(7)
    0
    >>> f(70)
    9
    >>> f(700)
    98