Relay questions can come in many forms. They typically start with let T = TNYWR (The Number You Will Receive). The idea is you can do a lot of work on solving the problem before you know what T is. Then when you receive T from a teammate, you can finish up your problem and get your answer.[br][br]Relays appear on [url]mathleague.org[/url] High School competitions and on ARML, [url]www.arml.com[/url], competitions.[br][br]This particular question is explained at [url]http://puzzles.nigelcoldwell.co.uk/twentyseven.htm[/url], along with lots of other places. A video explanation is at [url]https://www.youtube.com/watch?v=HUkN-AuYs2I[/url][br][br]An extension of the problem is explained on a video at [url]http://mathcounts.org/resources/video-library/mathcounts-minis/mini-21-counting-rectangles-gridsquares-lattice-grid[/url]