
theorem Th1298:
Sum digits(4000,10) = 4
proof
  thus Sum digits(4000,10) = Sum <%0,0,0%>+Sum <%4%> by Th1297,AFINSQ_2:55
  .= Sum <%0,0%> + Sum <%0%> + Sum <%4%> by AFINSQ_2:55
  .= (0 + 0) + Sum <%0%> + Sum <%4%> by AFINSQ_2:54
  .= (0 + 0 + 0) + Sum <%4%> by AFINSQ_2:53
  .= 4 by AFINSQ_2:53;
end;
