change([H,Q,D,N,P]) :- member(H,[0,1,2]), /* Half-dollars */ member(Q,[0,1,2,3,4]), /* quarters */ member(D,[0,1,2,3,4,5,6,7,8,9,10]) , /* dimes */ member(N,[0,1,2,3,4,5,6,7,8,9,10, /* nickels */ 11,12,13,14,15,16,17,18,19,20]), S is 50*H + 25*Q +10*D + 5*N, S =< 100, P is 100-S. % ?- change([H,Q,D,N,P]). % ?- change([0,2,3,4,6]). % ?- change([0,2,3,2,P]).