
theorem Th988:
Sum digits(943,10) = 16
proof
  thus Sum digits(943,10) = Sum <%3,4%>+Sum <%9%> by Th987,AFINSQ_2:55
  .= (3 + 4) + Sum <%9%> by AFINSQ_2:54
  .= 7 + 9 by AFINSQ_2:53
  .= 16;
end;
