Recently, I was watching a game of darts on the television. I don't watch or play much darts. The commentator mentioned something I'd not realised before. The player at the oche was on a total of 165, resulting in the commentator saying, "That's unlucky, 165 is one of the numbers that can't be made with a three-dart checkout." I immediately thought about how I could use this in a maths investigation.
With a bit of research, I found this list of possible darts checkouts. And, I made the following resource to explain the investigation. Today, some of my Year Five children successfully completed the investigation and found it to be an 'interesting challenge'.