
theorem Th637:
Sum digits(3080,10) = 11
proof
  thus Sum digits(3080,10) = Sum <%0,8,0%>+Sum <%3%> by Th636,AFINSQ_2:55
  .= Sum <%0,8%> + Sum <%0%> + Sum <%3%> by AFINSQ_2:55
  .= (0 + 8) + Sum <%0%> + Sum <%3%> by AFINSQ_2:54
  .= (0 + 8 + 0) + Sum <%3%> by AFINSQ_2:53
  .= 8 + 3 by AFINSQ_2:53
  .= 11;
end;
