Trying to do a simple calculation with a button

For a project I’m trying to make a type of calculator. Where I’m having trouble with is changing my button value to what I want the calculation output to be

here is a small portion of my html because its a big table but I’m trying to make a button like this one for all of them… enter image description here

here is the function I made for the calculations enter image description here

lastly, this is my web page so far
enter image description here

again, my goal is to change the “press” to the calculated value. Thank you! I hope this makes sense