
theorem Th112:
Sum digits(78,10) = 15
proof
  thus Sum digits(78,10) = Sum <%8%>+Sum <%7%> by Th111,AFINSQ_2:55
  .= 8 + Sum <%7%> by AFINSQ_2:53
  .= 8+7 by AFINSQ_2:53
  .= 15;
end;
