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> But you can make tricks for base 16 or 256 if you really need to check for a certain divisibility multiple times You don't need any tricks in that case since
by qayxc 6y ago
> But you can make tricks for base 16 or 256 if you really need to check for a certain divisibility multiple times
You don't need any tricks in that case since a simple bit mask (bit-wise AND) will do the trick then.
- raverbashing 6y agoNo bitmask will give you divisibility by 3 in base 16 In this case (division by 3 in mod 16) is the same as base 10: if the sum of digits is divisible by 3 then it is divisible (and the "extra digits" are 'c' and 'f') Examples: 0x3c (60) -> sum = 0xf (divisible) 0x2d (45) -> sum = 0xf (divisible)
- rjmunro 6y agoI may be misunderstanding - a bit mask only tells you if something is divisible by 16 or 256 (or any other power of 2) I think he's saying in base 16 you can make a trick to check divisibility by e.g. 15 in the same way you can check divisibility by 9 in base 10. So is 0xE1 (225) divisible by 0xF (15)? 0xE + 0x1 = 0xF, so yes.
- qayxc 6y ago> I think he's saying in base 16 you can make a trick to check divisibility by e.g. 15 in the same way you can check divisibility by 9 in base 10. Yeah - I misunderstood there and thought they meant divisibility by 16 or 256 not in base 16 or 256. Should've had my morning coffee first :D