
theorem Th108:
Sum digits(52,10) = 7
proof
  thus Sum digits(52,10) = Sum <%2%>+Sum <%5%> by Th107,AFINSQ_2:55
  .= 2 + Sum <%5%> by AFINSQ_2:53
  .= 2+5 by AFINSQ_2:53
  .= 7;
end;
