I'm trying to find the last five non-zero digits of a large factorial.
So for:
!10x = 3628800
the answer would be 36288 while for:
!20x = 2432902008176640000
the answer would be 17664.
I'm trying to do this by calculating /* 1+i.1000 without calculating
large numbers by losing the trailing zeroes at each step and the
leading digits more than five. Here's what I have so far:
(((|.&.":)@(5{.":&(|.&.":)))@*)/ 1+i.20x
The truncating code:
-- Converts to string, transposes, and converts back to a number.
That loses trailing zeroes (because they're now leading zeroes).
-- Converts to string and grabs the first five characters (which
were the last five non-zero digits).
-- Converts to string again -- not sure why this is necessary, but
it doesn't work otherwise -- transposes, and converts back to a number.
This whole thing is performed atop *, and the resulting verb is
inserted into the list from 1 to a large number.
This seems to work for large numbers up to 10049x. At 10050x I get an
ill-formed number error.
Where did I go wrong?
regards,
Geoff
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