This quilting technique fromQuilting Blocks & Patternson Youtube will help you, especially if youre new to quilting.
This tutorial will teach you two methods on how to square up a half-square triangle block.
Its quick, easy, and a clear method of how to do this properly.

Image credits: Quilting Blocks & Patterns via Youtube
Watch the video tutorial below to learn.
Do the same on the other end.
Now, cut the excess fabric.

You have now a 66 block.
How To Square Up A Half Square Triangle Quilting Block
