Weird, my 7 with a slash is consistently (2/2 times) recognised as a 7. Maybe you need to write the slash without connecting it to the bottom with a little loop? Otherwise it's a real shame that these networks are only trained on American handwriting (is it even handwriting? most Americans seem to print-write).

Hmmm... I don't connect with a loop. See the following: http://i.imgur.com/H7sYLNn.png I'd love to see what yours looks like.

Not the person you were talking to, but here's mine:

http://imgur.com/a/7OIgK

(American here). I did get it saying 3 a few times, but 7 most of the time.