Most recently made quilt rulers have a little slash for 7/8" marker.
They are easily available at your local Joann's store.
I'm going to assume that the directions call for cutting the squares in half to make triangles after you cut the strips, right?
Do you have a picture of the finished quilt (or pattern name)?
If you can post it, there are better, smarter ways to make the same shapes you need (without needing the 7/8" marker). :wink: