Talk:Lens-Maker's Glasses/@comment-91.77.75.24-20131124202046/@comment-89.98.67.81-20131129141138

Another possibility is that it goes like this:

1 lens = 10% for 2x.

10 lens = 100% for 2x, 0% for 3x.

11 lens = 100 % for 2x, 10% for 3x.

25 lens = 100% for 3x, 50% for 4x.