
theorem Th1332:
Sum digits(4425,10) = 15
proof
  thus Sum digits(4425,10) = Sum <%5,2,4%>+Sum <%4%> by Th1331,AFINSQ_2:55
  .= Sum <%5,2%> + Sum <%4%> + Sum <%4%> by AFINSQ_2:55
  .= (5 + 2) + Sum <%4%> + Sum <%4%> by AFINSQ_2:54
  .= (5 + 2 + 4) + Sum <%4%> by AFINSQ_2:53
  .= 11 + 4 by AFINSQ_2:53
  .= 15;
end;
