
theorem Th715:
Sum digits(3860,10) = 17
proof
  thus Sum digits(3860,10) = Sum <%0,6,8%>+Sum <%3%> by Th714,AFINSQ_2:55
  .= Sum <%0,6%> + Sum <%8%> + Sum <%3%> by AFINSQ_2:55
  .= (0 + 6) + Sum <%8%> + Sum <%3%> by AFINSQ_2:54
  .= (0 + 6 + 8) + Sum <%3%> by AFINSQ_2:53
  .= 14 + 3 by AFINSQ_2:53
  .= 17;
end;
