Just make sure you use this if you use toms solution. Gotta make sure your quotes are set up properly. quotes inside quotes only work if they are different quote times, I.e. singles can’t go in singles, doubles can’t go in doubles. Notice how the template below is all red? that’s because the whole thing is a string where as the other one posted has black, which will try to evaluate that as a method/function.
value: "{{ states('input_number.slider1') | int + 10 }}"