
theorem Th998:
Sum digits(1081,10) = 10
proof
  thus Sum digits(1081,10) = Sum <%1,8,0%>+Sum <%1%> by Th997,AFINSQ_2:55
  .= Sum <%1,8%> + Sum <%0%> + Sum <%1%> by AFINSQ_2:55
  .= (1 + 8) + Sum <%0%> + Sum <%1%> by AFINSQ_2:54
  .= (1 + 8 + 0) + Sum <%1%> by AFINSQ_2:53
  .= 9 + 1 by AFINSQ_2:53
  .= 10;
end;
