Hello LCMULLI and welcome to the Community.
Mike gave you sound advise and you definitely should contact your local building department. Also cinderblocks need to be installed on to a stable footing.
Without knowing the particulars about the dimensions of your walls, I can not give you an exact quantity. I can tell you that the surface of an 8" x 16" cinderblock is .89 sq. ft. If you calculate the sizes of your combined walls then divide by .89 you will find how many blocks you will need.
For example let say you have a room that is 20' by 25' by 8' high. That would be 20+20+25+25 times 8' = 720 sq. ft. of walls. You would divide 720 by .89 = 809 blocks. You should probably add at least 5% more for cutting which is a total of 849 blocks. Any extras you can return to the store.
Thank you for your inquiry.
Charlotte