
theorem Th277:
Sum digits(162,10) = 9
proof
  thus Sum digits(162,10) = Sum <%2,6%>+Sum <%1%> by Th276,AFINSQ_2:55
  .= (2 + 6) + Sum <%1%> by AFINSQ_2:54
  .= 8 + 1 by AFINSQ_2:53
  .= 9;
end;
