
theorem Th294:
Sum digits(152,10) = 8
proof
  thus Sum digits(152,10) = Sum <%2,5%>+Sum <%1%> by Th293,AFINSQ_2:55
  .= (2 + 5) + Sum <%1%> by AFINSQ_2:54
  .= 7 + 1 by AFINSQ_2:53
  .= 8;
end;
