
theorem Th1268:
Sum digits(3525,10) = 15
proof
  thus Sum digits(3525,10) = Sum <%5,2,5%>+Sum <%3%> by Th1267,AFINSQ_2:55
  .= Sum <%5,2%> + Sum <%5%> + Sum <%3%> by AFINSQ_2:55
  .= (5 + 2) + Sum <%5%> + Sum <%3%> by AFINSQ_2:54
  .= (5 + 2 + 5) + Sum <%3%> by AFINSQ_2:53
  .= 12 + 3 by AFINSQ_2:53
  .= 15;
end;
