Hair extensions, help?

Today I bought a pack of black hair extensions from Sally Beauty Supply. They are 8'' inches long and a few feet wide (intended for cutting into separate pieces) but i compared them to my actual hair and they are the same size? At the store inside of the pack they looked a lot longer but I was wrong. Is there any way I can make them longer using the rest of the hair or do I have to buy a longer pack? Thank you for your time.