# TITLE:  Fast Exponentiation, a^b (MOD m) without overflow 
# AUTHOR: Roy F.A. Maclean 
# EMAIL:  rfamgm at gmail
# WEB:    http://www.spiderpixel.co.uk/caspro                  
# DATE:   7Jun1998, 6Jun1999, 3Jul2007
# MAKE:   CASIO
# MODEL:  fx6300 or higher    
#
# Enables you to calculate a^b(mod m) without overflow
# as long as m<100000
#
# e.g. using this program 3^85 == 5(mod 17)
#
# Whereas if you tried calculating 3^85 directly before
# reducing modulo 17 then you would get round-off errors.             

@@ Program 1

"A"?->A:"B"?->B:"M"?->M
A-M*Int (A/M)->A                            
1->C:Lbl 1
Frac .5B<>0=>CA-M*Int (CA/M)->C    
Int .5B->B
AA-M*Int (AA/M)->A
B<>0=>Goto 1
C<0=>M+C->C
C