
theorem Th244:
Sum digits(289,10) = 19
proof
  thus Sum digits(289,10) = Sum <%9,8%>+Sum <%2%> by Th243,AFINSQ_2:55
  .= (9 + 8) + Sum <%2%> by AFINSQ_2:54
  .= 17 + 2 by AFINSQ_2:53
  .= 19;
end;
