File containing its own checksum

Question

Is it possible to create a file that will contain its own checksum (MD5, SHA1, whatever)? And to upset jokers I mean checksum in plain, not function calculating it.

Answer 1

Certainly, it is possible. But one of the uses of checksums is to detect tampering of a file - how would you know if a file has been modified, if the modifier can also replace the checksum?