Need help determing what formula to use

Hello guys and gals,

I have a problem with my homework since I have no idea what kind of formula to use. I have been searching for 1.5hour now to see which formula to use to determine the outcome but cant find one. I believe it has something to do with probability and uniform distribution.

Anyway here it goes:
The ministry of finance want to verify the reliablity of filled in tax sheets. Thereby they determined the frequency table of all filled in digits. This table can be seen on the left. The assumption is that every digit should have the same probability to be filled in ( 0: 1/10, 1: 1/10, ..., 9: 1/10)

a) Would you accept or reject the corresponding tax sheet?
b) Explain by mentioning the value of the necessary elements in this calculation (20 pt).*

With the following data:
digit occurences
0 12345
1 11321
2 11009
3 13333
4 12332
5 13112
6 13111
7 11112
8 12333
9 13333

I need help coming up with the way how to solve this and any other examples to practice on would be awesome.
That is the thing I kept coming back to but the problem is that we did not handle this in class and I cant find it in any sheets for the upcoming lectures so I dont think this is the one I should be using..:(