How many solutions to the 16 dot puzzle are there?

newinfiniteabyss: How many solutions to the 16 dot puzzle are there?
You know this old puzzle, a 4×4 grid of dots that you must connect with 6 straight lines without lifting your pen off the paper. I found one solution myself, and two different ones on the internet (one here on answers). Does anyone know how many different solutions there are?

Answers and Views:

Answer by xwdguy
My favorite solution is the one where the starting and ending place are the same. No endpoints are on the dots (or even within the 4×4 grid area). If we call the points
1a 1b 1c 1d
2a 2b 2c 2d
3a 3b 3c 3d
4a 4b 4c 4d
then line 1 sweeps thru 1a-4d diagonal,
next goes thru 3d + 1c, next thru 1b + 3a, next
thru 4a-1d diagonal, next 2d + 4c, next 4b + 2a
and connecting to start of first line.

I’m sure there are plenty of ways to do this omitting
the “start and end at the same place”.

Answer by stealtip
16