
theorem Th191:
Sum digits(192,10) = 12
proof
  thus Sum digits(192,10) = Sum <%2,9%>+Sum <%1%> by Th190,AFINSQ_2:55
  .= (2 + 9) + Sum <%1%> by AFINSQ_2:54
  .= 11 + 1 by AFINSQ_2:53
  .= 12;
end;
