
theorem Th290:
Sum digits(114,10) = 6
proof
  thus Sum digits(114,10) = Sum <%4,1%>+Sum <%1%> by Th289,AFINSQ_2:55
  .= (4 + 1) + Sum <%1%> by AFINSQ_2:54
  .= 5 + 1 by AFINSQ_2:53
  .= 6;
end;
