
theorem Th1286:
Sum digits(3825,10) = 18
proof
  thus Sum digits(3825,10) = Sum <%5,2,8%>+Sum <%3%> by Th1285,AFINSQ_2:55
  .= Sum <%5,2%> + Sum <%8%> + Sum <%3%> by AFINSQ_2:55
  .= (5 + 2) + Sum <%8%> + Sum <%3%> by AFINSQ_2:54
  .= (5 + 2 + 8) + Sum <%3%> by AFINSQ_2:53
  .= 15 + 3 by AFINSQ_2:53
  .= 18;
end;
