
theorem Th797:
Sum digits(924,10) = 15
proof
  thus Sum digits(924,10) = Sum <%4,2%>+Sum <%9%> by Th796,AFINSQ_2:55
  .= (4 + 2) + Sum <%9%> by AFINSQ_2:54
  .= 6 + 9 by AFINSQ_2:53
  .= 15;
end;
