They are adorable, Anna!! Thanks for sharing!

For those (like myself) that don't have Pinterest accounts, this is the link to the blog it comes from:
The Sewing Chick | A Christmas Tutorial ? Checkered Chargers

Can you discuss Maths on this forum (I mean, would it be considered language abuse? I'm certain my DH would!). Dresden rulers that have different angles just mean there will be a different number of wedges to complete the circle. In this case she needs 20 wedges, as her ruler is 360/20=18 degrees. But I bet the pattern would be just as pretty with slightly wider or narrower wedges, you'll only need to adapt the number of wedges you require.