I think just about any line-based 2D graphical symbol can have the "line number" determined...

e.g.

The following symbols involve the following numbers based on how many lines are involved:

3, 4, 2, 1...

Perhaps a 0 could be represented using a dot (0 lines) - the problem with that is that any number of dots would still be a 0.

The infinity symbol is a 1, a cross is a 2 (duality) but I'm not sure about the yin-yang symbol (depends if the inner "S" is joined to the outer circle). The pentagram is 5 and David's star is 6. On a related note, I was told that a 5 pointed star is a feminine star while the 6 pointed star is masculine.

This "heartagram" is a 3.

I plan on eventually making a website about this. ]]>