
theorem Th738:
Sum digits(231,10) = 6
proof
  thus Sum digits(231,10) = Sum <%1,3%>+Sum <%2%> by Th737,AFINSQ_2:55
  .= (1 + 3) + Sum <%2%> by AFINSQ_2:54
  .= 4 + 2 by AFINSQ_2:53
  .= 6;
end;
