
theorem Th942:
Sum digits(253,10) = 10
proof
  thus Sum digits(253,10) = Sum <%3,5%>+Sum <%2%> by Th941,AFINSQ_2:55
  .= (3 + 5) + Sum <%2%> by AFINSQ_2:54
  .= 8 + 2 by AFINSQ_2:53
  .= 10;
end;
