
theorem Th1350:
Sum digits(4650,10) = 15
proof
  thus Sum digits(4650,10) = Sum <%0,5,6%>+Sum <%4%> by Th1349,AFINSQ_2:55
  .= Sum <%0,5%> + Sum <%6%> + Sum <%4%> by AFINSQ_2:55
  .= (0 + 5) + Sum <%6%> + Sum <%4%> by AFINSQ_2:54
  .= (0 + 5 + 6) + Sum <%4%> by AFINSQ_2:53
  .= 11 + 4 by AFINSQ_2:53
  .= 15;
end;
