
theorem Th1258:
Sum digits(3350,10) = 11
proof
  thus Sum digits(3350,10) = Sum <%0,5,3%>+Sum <%3%> by Th1257,AFINSQ_2:55
  .= Sum <%0,5%> + Sum <%3%> + Sum <%3%> by AFINSQ_2:55
  .= (0 + 5) + Sum <%3%> + Sum <%3%> by AFINSQ_2:54
  .= (0 + 5 + 3) + Sum <%3%> by AFINSQ_2:53
  .= 8 + 3 by AFINSQ_2:53
  .= 11;
end;
