
theorem Th785:
Sum digits(748,10) = 19
proof
  thus Sum digits(748,10) = Sum <%8,4%>+Sum <%7%> by Th784,AFINSQ_2:55
  .= (8 + 4) + Sum <%7%> by AFINSQ_2:54
  .= 12 + 7 by AFINSQ_2:53
  .= 19;
end;
