TI-BASIC Modular Exponentiation (only works for 6-digit bases)

modexp.txt

Disp "X^Y MOD Z"
Prompt X,Y,Z

If Z<=1
Then
	Disp "ERROR"
	Return
End

1->W
round(Z*fPart(X/Z),0)->X

While Y>0
	ClrHome
	Disp W
	Disp "TIMES"
	Disp X
	Disp "TO THE"
	Disp Y
	Disp "=RESULT MOD"
	Disp Z
	Pause 
	
	If round(2*fPart(Y/2),0)=1
	Then
		round(Z*fPart((W*X)/Z),0)->W
	End
	
	iPart(Y/2)->Y
	round(Z*fPart((X*X)/Z),0)->X
End

ClrHome
Disp "RESULT="
Disp W
Disp "MOD"
Disp Z
Pause 
Stop