I am not clear on it being clearly one digit or another. Yes, one would normally see that as a '9' but I wonder if you could be interpreted as a '4' or a very strange '0' since the '9' does not seem to be an option. From the neighboring entries, it is clearly not 1,2,5,7, or 8 leaving 0, 3, 4, 6, and 9. The other '9' in the entries is a bit different with the rounded part closed rather than open but this could just be a random event. If there are more entries on the page, perhaps one can find samples of other digits for more clues (assuming the handwriting is all by one person). Even without additional clues, it is easy to rule out '3' and '6'