I think adding 7/8" squares was for the half squares where you got 2 out of 2 squares. I thought you'd have to add more for the quarter square. Here's another site I found for "Calculating Quarter Square Triangles":
http://www.patchwork-and-quilting.co...riangles.html. I have not had time to try this yet, so I can't vouch for it. If anyone tries it, and it works, please let me know. Thanks.