Scoring systems
In bowling a strike earns the next two balls as a bonus and a spare the next one, which makes keeping score by hand error-prone. In 501 darts you must hit exactly zero, finishing on a double. Golf’s World Handicap System averages the best 8 of your last 20 score differentials. In chess, the Elo system updates a rating by the gap between expected and actual result, multiplied by a K-factor.
Weight classes
Boxing, wrestling, judo, MMA, taekwondo, kickboxing and weightlifting match athletes by weight class, and the limits differ between federations. The weight class finder shows which division your weigh-in weight puts you in. Always check the current rules of the relevant federation before an official competition.