
theorem Th645:
Sum digits(3160,10) = 10
proof
  thus Sum digits(3160,10) = Sum <%0,6,1%>+Sum <%3%> by Th644,AFINSQ_2:55
  .= Sum <%0,6%> + Sum <%1%> + Sum <%3%> by AFINSQ_2:55
  .= (0 + 6) + Sum <%1%> + Sum <%3%> by AFINSQ_2:54
  .= (0 + 6 + 1) + Sum <%3%> by AFINSQ_2:53
  .= 7 + 3 by AFINSQ_2:53
  .= 10;
end;
