Sentences with Back Number

The archaeologist discovered artifacts that were once cutting-edge but were now considered back number tools.

The old computer software became a back number when the company released a more advanced and efficient version.

The elderly storyteller shared tales of back number customs and traditions that had faded with the passing years.

The vintage car model, though a back number in terms of technology, still attracts car enthusiasts with its unique design.

The manual typewriter, once a staple in offices, is now viewed as a back number with the rise of computer keyboards.