
theorem Th1310:
Sum digits(4150,10) = 10
proof
  thus Sum digits(4150,10) = Sum <%0,5,1%>+Sum <%4%> by Th1309,AFINSQ_2:55
  .= Sum <%0,5%> + Sum <%1%> + Sum <%4%> by AFINSQ_2:55
  .= (0 + 5) + Sum <%1%> + Sum <%4%> by AFINSQ_2:54
  .= (0 + 5 + 1) + Sum <%4%> by AFINSQ_2:53
  .= 6 + 4 by AFINSQ_2:53
  .= 10;
end;
