Just like traditional battleship except instead of coordinates they use the answer to times table questions to try to locate their opponent's ship.
E.G Player 1 asks the other 'Is it in 36?' so then Player 2 looks to see if they put their ship in the 6 x 6 grid square.
It revises the 5, 6, 7, 8, 9 and 10 times tables. Students play in pairs with a game board each. I recommend laminating the cards so whiteboard markers can be used to draw ships and then easily removed.