Oops, I think the display broke because the text isn’t resized. The calculations should be the same as the target score shown on the page.
I replaced the auto-resizing text I had in the current game with a better third-party one, the bug should be fixed now.
The word in the score preview (before the 10 x 3.24) will turn red when you’re about to play a used word. I’ll make it more clear in-game by making it say (USED) before the word, while still turning red.