
theorem Th99:
Sum digits(48,10) = 12
proof
  thus Sum digits(48,10) = Sum <%8%>+Sum <%4%> by Th98,AFINSQ_2:55
  .= 8 + Sum <%4%> by AFINSQ_2:53
  .= 8+4 by AFINSQ_2:53
  .= 12;
end;
