1. I am not entirely a back number, Taylor.
2. He is a back number.
3. Never mind about him, he's a back number.
4. This building has become a back number in design.
5. Never mind about him. He's a back number.
6. Maybe I'm a back number. I can never enjoy a play of staccato scenes.
7. It does not matter. It was a back number anyway.
8. It doesn't matter , It was a back number anyway.