This is the seventh note in a series of seven notes on QBasic. The topics discussed in this note are: (i) need for external data files, (ii) different types of file organization, (iii) structure of sequential files, (iv) opening and closing a file, (v) how to create new sequential file, (vi) how to read a sequential file, (vii) how to append data to an existing sequential file, and (viii) dealing with more than one sequential file in one program. The note has a set of eight exercise problems.