And springing to mine: Pocket PC with J (I wish).
Matthew Brand wrote: > "p.s. In my youth, when I needed to remember a (5-digit) > number for a time, I would try to compute its largest > prime factor by mental calculation. Try it and you'll > see why that works." > > Three words spring to mind. Pen. Paper. Pocket. :-)). > > > 2009/8/22 Roger Hui <[email protected]>: >> The problem is that _every_ number has something >> notable about it, so that each number is "unforgettable" >> and consequently it's hard to remember any single >> one of them. >> >> 0000 all zeros >> 0001 first counting number >> 0002 first prime number >> 0003 first odd prime >> 0004 first composite number >> ... >> 24 60 #: ?. */ 24 60 >> 1 6 >> >> 0106 first number greater than 100 with 2 prime factors >> >> etc. >> >> You have most likely heard of the story about Hardy >> and Ramanujan. One day Hardy took a taxi to visit >> Ramanujan. On arriving Hardy told Ramanujan that >> the taxi had the 4-digit number n on its license plate, >> a thoroughly unremarkable number. Ramanujan >> immediately remarked that n is the first number that ... . >> I forget what n or the property was, something like, >> n is the first number that can be written as the sum >> of two perfect cubes in two different ways, something >> typically Ramanujanish. >> >> Yes, that was it: >> >> c=: i*i*i=: >:i.200 >> t=: (</~i.200) * +/~c >> d=: </.~ ,t >> (2=#&>d)#d >> +---------+---------------+---------------+---------+-- >> |1729 1729|1092728 1092728|3375001 3375001|4104 4104| ... >> +---------+---------------+---------------+---------+-- >> <./ {.&> (2=#&>d)#d >> 1729 >> I. , 1729 = t >> 11 1609 >> 1 + (#t) #: 11 1609 >> 1 12 >> 9 10 >> +/ 1 12 ^ 3 >> 1729 >> +/ 9 10 ^ 3 >> 1729 >> >> Now that I have worked out the number I can find the >> story on the net: http://en.wikipedia.org/wiki/1729_(number) >> >> p.s. In my youth, when I needed to remember a (5-digit) >> number for a time, I would try to compute its largest >> prime factor by mental calculation. Try it and you'll >> see why that works. >> >> >> >> ----- Original Message ----- >> From: Kip Murray <[email protected]> >> Date: Saturday, August 22, 2009 5:27 >> Subject: Re: [Jprogramming] Unforgettable times >> To: Programming forum <[email protected]> >> >>> To narrow the puzzle, >>> >>> times 3 4 5 NB. Unforgettable >>> 1 6 2 0 >>> 1 8 1 2 >>> 1 2 0 7 >>> timedata i. 1 8 1 2 >>> 4 >>> times i.8 >>> 1 2 3 4 >>> 1 4 1 4 >>> 1 4 2 8 >>> 1 6 2 0 >>> 1 8 1 2 >>> 1 2 0 7 >>> 1 2 3 4 >>> 1 4 1 4 >>> >>> You are encouraged to choose your own unforgettable times seen >>> on a 24-hour >>> digital clock. >>> >>> >>> Kip Murray wrote: >>>> Who could forget >>>> >>>> times 3 4 5 >>>> 1 6 2 0 >>>> 1 8 1 2 >>>> 1 2 0 7 >>>> >>>> ? >>>> >>>> Kip Murray wrote: >>>>> Write a verb that produces unforgettable times on a 24-hour >>> digital clock: who >>>>> could forget an appointment at 12:34 or 14:14 or 14:28 >>> ? It's too bad that >>>>> 31:41 , 27:18 and 69:31 do not fit on the clock. >>>>> >>>>> times 0 >>>>> 1 2 3 4 >>>>> times 0 1 >>>>> 1 2 3 4 >>>>> 1 4 1 4 >>>>> times i. 5 >>>>> 1 2 3 4 >>>>> 1 4 1 4 >>>>> 1 4 2 8 >>>>> 1 2 3 4 >>>>> 1 4 1 4 >>>>> NB. Oh, well, you will do >>> better than this >> ---------------------------------------------------------------------- >> For information about J forums see http://www.jsoftware.com/forums.htm >> > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
