
theorem Th1160:
Sum digits(1725,10) = 15
proof
  thus Sum digits(1725,10) = Sum <%5,2,7%>+Sum <%1%> by Th1159,AFINSQ_2:55
  .= Sum <%5,2%> + Sum <%7%> + Sum <%1%> by AFINSQ_2:55
  .= (5 + 2) + Sum <%7%> + Sum <%1%> by AFINSQ_2:54
  .= (5 + 2 + 7) + Sum <%1%> by AFINSQ_2:53
  .= 14 + 1 by AFINSQ_2:53
  .= 15;
end;
