Is it normal that i write some of my numbers bottom to top?

I write most numbers from bottom to top. I am not sure why but its just the way I have always done it and I have had a few people comment on how I write my numbers backwards. I figured such a trivial thing would be a "to each their own" sort of thing, but a few people who have commented on it basically implied that I write them wrong and that the educational system failed me. It sadly made me insecure enough to create this post.