
theorem Th958:
Sum digits(552,10) = 12
proof
  thus Sum digits(552,10) = Sum <%2,5%>+Sum <%5%> by Th957,AFINSQ_2:55
  .= (2 + 5) + Sum <%5%> by AFINSQ_2:54
  .= 7 + 5 by AFINSQ_2:53
  .= 12;
end;
