
theorem Th1168:
Sum digits(1850,10) = 14
proof
  thus Sum digits(1850,10) = Sum <%0,5,8%>+Sum <%1%> by Th1167,AFINSQ_2:55
  .= Sum <%0,5%> + Sum <%8%> + Sum <%1%> by AFINSQ_2:55
  .= (0 + 5) + Sum <%8%> + Sum <%1%> by AFINSQ_2:54
  .= (0 + 5 + 8) + Sum <%1%> by AFINSQ_2:53
  .= 13 + 1 by AFINSQ_2:53
  .= 14;
end;
