
theorem Th1152:
Sum digits(1550,10) = 11
proof
  thus Sum digits(1550,10) = Sum <%0,5,5%>+Sum <%1%> by Th1151,AFINSQ_2:55
  .= Sum <%0,5%> + Sum <%5%> + Sum <%1%> by AFINSQ_2:55
  .= (0 + 5) + Sum <%5%> + Sum <%1%> by AFINSQ_2:54
  .= (0 + 5 + 5) + Sum <%1%> by AFINSQ_2:53
  .= 10 + 1 by AFINSQ_2:53
  .= 11;
end;
