
theorem Th1122:
Sum digits(1025,10) = 8
proof
  thus Sum digits(1025,10) = Sum <%5,2,0%>+Sum <%1%> by Th1121,AFINSQ_2:55
  .= Sum <%5,2%> + Sum <%0%> + Sum <%1%> by AFINSQ_2:55
  .= (5 + 2) + Sum <%0%> + Sum <%1%> by AFINSQ_2:54
  .= (5 + 2 + 0) + Sum <%1%> by AFINSQ_2:53
  .= 7 + 1 by AFINSQ_2:53
  .= 8;
end;
