
theorem Th1358:
Sum digits(4750,10) = 16
proof
  thus Sum digits(4750,10) = Sum <%0,5,7%>+Sum <%4%> by Th1357,AFINSQ_2:55
  .= Sum <%0,5%> + Sum <%7%> + Sum <%4%> by AFINSQ_2:55
  .= (0 + 5) + Sum <%7%> + Sum <%4%> by AFINSQ_2:54
  .= (0 + 5 + 7) + Sum <%4%> by AFINSQ_2:53
  .= 12 + 4 by AFINSQ_2:53
  .= 16;
end;
