I've noticed that people coming from English-speaking countries tend to write "1" without the upstroke and "7" without a dash:
which differs from the way the numbers are usually written in continental Europe1:
Is there any particular (historical?) reason for this?
1 According to Wikipedia, "most people in Continental Europe, Latin America, and New England write 7 with a line in the middle ("7"), sometimes with the top line crooked."