
theorem Th1288:
Sum digits(3850,10) = 16
proof
  thus Sum digits(3850,10) = Sum <%0,5,8%>+Sum <%3%> by Th1287,AFINSQ_2:55
  .= Sum <%0,5%> + Sum <%8%> + Sum <%3%> by AFINSQ_2:55
  .= (0 + 5) + Sum <%8%> + Sum <%3%> by AFINSQ_2:54
  .= (0 + 5 + 8) + Sum <%3%> by AFINSQ_2:53
  .= 13 + 3 by AFINSQ_2:53
  .= 16;
end;
