Scrabble variants require scientific notation, depending on the board. Points are calculated automatically and displayed next to definitions of words as they are placed. Anadrome has a tile-earning mechanic and board editor, allowing users to create publicly available boards for Scrabble, Words with Friends, and their own custom designs, making it a superset of crossword-style games. On the game show "Scrabble Showdown", two teams play various games in order to win prizes including a vacation to anywhere in the world. Gosum is similar to Numble. Users place sequences of numbers and equations, using the four main arithmetic operators (addition, subtraction, division, multiplication)
Challenge (Scrabble) has not seen a single drawn tile yet, in order to consider whether to challenge. To do this, the player simply announces, "Hold," which prevents the opponent from drawing replenishment tiles for 15 seconds (but may draw thereafter, keeping those tiles separate). The player may decide to rescind the hold, or challenge the play. Scrabble and Scrabble-like game sites on the Internet such as Yahoo! Games' Literati, Internet Scrabble Club and Lexulous offer automatic verification as an option, which makes it impossible to play an invalid word. The Facebook version of Scrabble and Zynga's mobile game Words With Friends make