
theorem Th691:
Sum digits(3620,10) = 11
proof
  thus Sum digits(3620,10) = Sum <%0,2,6%>+Sum <%3%> by Th690,AFINSQ_2:55
  .= Sum <%0,2%> + Sum <%6%> + Sum <%3%> by AFINSQ_2:55
  .= (0 + 2) + Sum <%6%> + Sum <%3%> by AFINSQ_2:54
  .= (0 + 2 + 6) + Sum <%3%> by AFINSQ_2:53
  .= 8 + 3 by AFINSQ_2:53
  .= 11;
end;
