Sasha Pachev wrote: > I just came up with this while teaching my son about numbers. Let's > see how quickly somebody figures this out. > > If you had a 64 bit number written down in hex, how could you quickly > tell without the aid of any computational device, including pencil or > paper if it is divisible by 15? > > How about 17?
For 15: If you add up the numeric value of each digit, it should total 15. Did your son come up with an answer? If so, great job! --Dave /* PLUG: http://plug.org, #utah on irc.freenode.net Unsubscribe: http://plug.org/mailman/options/plug Don't fear the penguin. */
