
theorem Th1262:
Sum digits(3425,10) = 14
proof
  thus Sum digits(3425,10) = Sum <%5,2,4%>+Sum <%3%> by Th1261,AFINSQ_2:55
  .= Sum <%5,2%> + Sum <%4%> + Sum <%3%> by AFINSQ_2:55
  .= (5 + 2) + Sum <%4%> + Sum <%3%> by AFINSQ_2:54
  .= (5 + 2 + 4) + Sum <%3%> by AFINSQ_2:53
  .= 11 + 3 by AFINSQ_2:53
  .= 14;
end;
