
theorem Th559:
Sum digits(2300,10) = 5
proof
  thus Sum digits(2300,10) = Sum <%0,0,3%>+Sum <%2%> by Th558,AFINSQ_2:55
  .= Sum <%0,0%> + Sum <%3%> + Sum <%2%> by AFINSQ_2:55
  .= (0 + 0) + Sum <%3%> + Sum <%2%> by AFINSQ_2:54
  .= (0 + 0 + 3) + Sum <%2%> by AFINSQ_2:53
  .= 3 + 2 by AFINSQ_2:53
  .= 5;
end;
