Each position in rugby union has an assigned number. Usually, the starters will wear numbers one through 15, while the eight reserves will wear 16 through 23. The purpose of the numbers are to make it easier to identify who has the ball and where the players are supposed to be. The numbers also make it easy for the referee to give out yellow and red cards to players who have committed fouls.
There are two props on every team. They wear numbers one and number three depending on what side of the scrum they play. The props are called:
They wear number two. There is always one hooker on every team.
There are two locks on each team. They wear numbers four and five.
There are two flankers on each team. They wear numbers six and seven.
There is one number eight on each team. Oddly enough, they wear the number eight.
A back called the scrum half wears the number nine on the field. There is only one scrum half on the team.
There is one fly half on the team. They wear number 10.
There are two wingers on each team. They wear numbers 11 and 14.
There are two centers on each team. They wear numbers 12 and 13. There are two types of centers:
There is one full back on each team. They wear number 15.