RPL exercise - Last Digits of Primes (HP 49G, G+, 50g)

[Gerson W. Barbosa]

Thank you all for your participation and for the interesting and efficient solutions.

Here are my rather convoluted ones:

Base 10:

Code:


%%HP: T(3)A(R)F(,);
\<< DUP { } SWAP 5 1 ROT
  START NEXTPRIME SWAP OVER \->STR DUP SIZE DUP SUB OBJ\-> + SWAP
  NEXT DROP 2 * 1 - \PILIST FACTOR \->STR "*" "''" SREPL DROP OBJ\-> 3 \->LIST LN { 5 13 17 } LN / EXPAND SWAP OVER \GSLIST - SWAP +
\>>

I had tried 10 MOD instead of \->STR DUP SIZE DUP SUB OBJ\-> above, but akwardly the running time would increase from 155.4 s to 1677.1 s, for 1000 primes.

Base 8:

Code:


%%HP: T(3)A(R)F(,);
\<< DUP OCT { } SWAP 2 1 ROT
  START NEXTPRIME SWAP OVER R\->B \->STR DUP SIZE 1 - DUP SUB OBJ\-> + SWAP
  NEXT DROP 8 - NEG \PILIST FACTOR \->STR "*" "''" SREPL DROP OBJ\-> 3 \->LIST LN { 3 5 7 } LN / EXPAND REVLIST SWAP OVER \GSLIST - +
\>>