
theorem Th635:
Sum digits(3060,10) = 9
proof
  thus Sum digits(3060,10) = Sum <%0,6,0%>+Sum <%3%> by Th634,AFINSQ_2:55
  .= Sum <%0,6%> + Sum <%0%> + Sum <%3%> by AFINSQ_2:55
  .= (0 + 6) + Sum <%0%> + Sum <%3%> by AFINSQ_2:54
  .= (0 + 6 + 0) + Sum <%3%> by AFINSQ_2:53
  .= 6 + 3 by AFINSQ_2:53
  .= 9;
end;
