
theorem Th811:
Sum digits(1078,10) = 16
proof
  thus Sum digits(1078,10) = Sum <%8,7,0%>+Sum <%1%> by Th810,AFINSQ_2:55
  .= Sum <%8,7%> + Sum <%0%> + Sum <%1%> by AFINSQ_2:55
  .= (8 + 7) + Sum <%0%> + Sum <%1%> by AFINSQ_2:54
  .= (8 + 7 + 0) + Sum <%1%> by AFINSQ_2:53
  .= 15 + 1 by AFINSQ_2:53
  .= 16;
end;
