
theorem Th695:
Sum digits(3660,10) = 15
proof
  thus Sum digits(3660,10) = Sum <%0,6,6%>+Sum <%3%> by Th694,AFINSQ_2:55
  .= Sum <%0,6%> + Sum <%6%> + Sum <%3%> by AFINSQ_2:55
  .= (0 + 6) + Sum <%6%> + Sum <%3%> by AFINSQ_2:54
  .= (0 + 6 + 6) + Sum <%3%> by AFINSQ_2:53
  .= 12 + 3 by AFINSQ_2:53
  .= 15;
end;
