
theorem Th1322:
Sum digits(4300,10) = 7
proof
  thus Sum digits(4300,10) = Sum <%0,0,3%>+Sum <%4%> by Th1321,AFINSQ_2:55
  .= Sum <%0,0%> + Sum <%3%> + Sum <%4%> by AFINSQ_2:55
  .= (0 + 0) + Sum <%3%> + Sum <%4%> by AFINSQ_2:54
  .= (0 + 0 + 3) + Sum <%4%> by AFINSQ_2:53
  .= 3 + 4 by AFINSQ_2:53
  .= 7;
end;
