
theorem Th1002:
Sum digits(1127,10) = 11
proof
  thus Sum digits(1127,10) = Sum <%7,2,1%>+Sum <%1%> by Th1001,AFINSQ_2:55
  .= Sum <%7,2%> + Sum <%1%> + Sum <%1%> by AFINSQ_2:55
  .= (7 + 2) + Sum <%1%> + Sum <%1%> by AFINSQ_2:54
  .= (7 + 2 + 1) + Sum <%1%> by AFINSQ_2:53
  .= 10 + 1 by AFINSQ_2:53
  .= 11;
end;
