[Sealy]

That is pretty cool. It would be handy if I can see the multiples of 7 that I have used already. That way I can figure out what to work towards next.

[zsch]

That's a great idea! The trick will be finding a place to display it. Maybe I'll add a button next to the score, and clicking it will reveal an overlay with played numbers.

[Sealy]

A button would be good, but it would be even better if it showed up as soon as you played it. It would reduce the number of unnecessary clicks then and become more intuitive to play.

[jstanley]

You could just display the smallest multiple of seven that hasn't been used yet.