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Shishir wrote:
> Hi All,
>
>
> Suppose we have a 32 bit binary number. We can tell it is divisible
> by looking at the rightmost one bit. If it zero , it is divisible by 2.
> If rightmost two bits are zeros then the number is divisible by 4 . If
> rightmost three bits are zeros the number is divisible by 8 and so on.
>
> Could anyone has some idea on divisibility of binary numbers by 3,5,6,7
> .....
>
>
> Regards,
> Shishir
Hi,
I call it digit summation congruence or DSC and it is discussed here,
on sci.math, in implementation details and so forth, factorization
methods for binary computers.
Basically you can group the binary digits, bits, from the right in
groups of say, n, and then if the sum of those groups is divisible by
2^n-1, the Mersenne number that is a binary rep-unit, then the extended
precision sequence is divisible by that number.
If you want to test for divisbility by 2^n+1, perhaps it is,
alternately add and subtract the groups and test that sum for
divisbility by the number.
There are a wide variety of divisbility tests, specific to number,
base, totient, etcetera.
Regards,
Ross F.
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