Here is my Aunt Dinah block. This one calls for 4-7/8 and 2-7/8 squares and what I did was rounded up and cut them 5 and 3, then squared up the block sections. I've found this works better for me recently. That little bit of extra allows forgiveness for seam allowances, slippage of fabric when sewing and maybe slight pressing distortion. And I have a hard time seeing that 7/8 line on my rulers.