
theorem Th477:
Sum digits(1480,10) = 13
proof
  thus Sum digits(1480,10) = Sum <%0,8,4%>+Sum <%1%> by Th476,AFINSQ_2:55
  .= Sum <%0,8%> + Sum <%4%> + Sum <%1%> by AFINSQ_2:55
  .= (0 + 8) + Sum <%4%> + Sum <%1%> by AFINSQ_2:54
  .= (0 + 8 + 4) + Sum <%1%> by AFINSQ_2:53
  .= 12 + 1 by AFINSQ_2:53
  .= 13;
end;
