
theorem Th1370:
Sum digits(4900,10) = 13
proof
  thus Sum digits(4900,10) = Sum <%0,0,9%>+Sum <%4%> by Th1369,AFINSQ_2:55
  .= Sum <%0,0%> + Sum <%9%> + Sum <%4%> by AFINSQ_2:55
  .= (0 + 0) + Sum <%9%> + Sum <%4%> by AFINSQ_2:54
  .= (0 + 0 + 9) + Sum <%4%> by AFINSQ_2:53
  .= 9 + 4 by AFINSQ_2:53
  .= 13;
end;
