We are told to "Cut 2 side borders each 10" x 81". Cut the top and bottom borders each 10" x 65".
The assembled measurement of the units we have already completed will be 63", so I am assuming that the width will also be trimmed after the borders are appliqued.
When I cut my long borders, I will starch a length of fabric as directed. They have already added a couple of inches to the length.
I will simply fold the starched fabric length in half twice, being sure to line up the selvage edges and use my 24" ruler to cut off the selvage edge then cut the 10" wide strips.
Because these are to be cut so wide, we are basically cutting our yardage in fourths, but to make trimming easier later, I will go ahead and cut the 10" widths instead of just chopping it into quarters.