of which are disregarded. In 3×3×3 blindfolded and 3×3×3 fewest moves challenges, either straight mean of 3 or best of 3 is used, while 4×4×4 blindfolded, 5×5×5 blindfolded, and multiple blindfolded challenges are ranked using best of 1, 2 or 3, depending on the competition. When a round begins, competitors hand in the puzzle they will use. Puzzles are scrambled using a computer-generated scramble. Each round, five, three or one (depending on the format, mentioned above) scrambles are used. Every competitor in the round will receive each scramble once. Before starting a solve, a competitor has up to 15 seconds to inspect the puzzle (inspection is removed for blindfolded events). This is monitored by a judge with a stopwatch. Once the solve is complete, the judge records the time on the competitor's scorecard and it is signed by both. If the puzzle is unsolved and the timer is stopped, the time is recorded as "DNF" (Did Not Finish). There are also numerous reasons why the solve can receive a two-second addition to the solve time, such as a face being more than 45 degrees off, or the competitor going over the allowed inspection time. A competitor can also receive an extra solve to replace the one just completed, for example in the case of a timer malfunction or a duplicate scramble. The official timer used in competitions is the StackMat timer. This device has touch-sensitive pads that are triggered by the user lifting one or both of their hands to start the time and placing both their hands back on the pads after releasing the puzzle to stop the timer. Official competitions are currently being held in several categories. Competitions will often include events for speedsolving other puzzles as well, such as: Pyraminx, a pyramid shaped puzzle. Megaminx, an twelve sided puzzle similar to a 3x3x3. Skewb, a cube shaped puzzle. Square-1, a cubed puzzle that changes shape as it is solved Rubik's Clock, a double sided circle shaped puzzle with many clocks on it that is considered solved when all clock hands are in the 12 o'clock position. World Rubik's Cube Championships The WCA organizes the Rubik's Cube World Championship as the main international competition once every two years. The latest championship was held in Melbourne, Australia from 11 to 14 July 2019. World records The following are the official speedcubing world records approved by the WCA. Note: For