60 triangles. This ruler is fabulous for many sizes of triangles.
Cut a strip e.g. 4 and 1/4" if you are wanting a 4 and 1/4" triangle.
You may cut several layers at one time, ensuring that your strips are level.
Use scraps or one light fabric and one dark.
I am sorry to have used varying types of fabric as I got carried away piecing them and then had to cut more from different fabrics to show the steps.
Below- Top and tail the triangular ruler (as in the grey fabrics- which I have separated to show the cuts.)
Below :- I put a dot on the straight grain while the triangles were still basically in their cut position, so my straight grain would be along the length of e.g a border strip.
Below:- If making a strip or border:- Alternate a light and a dark for your strip. See my pic and refer to Lynette's pirate pattern