
theorem Th93:
Sum digits(12,10) = 3
proof
  thus Sum digits(12,10) = Sum <%2%>+Sum <%1%> by Th92,AFINSQ_2:55
  .= 2 + Sum <%1%> by AFINSQ_2:53
  .= 2+1 by AFINSQ_2:53
  .= 3;
end;
