What is the signifcance of numbers on football jerseys?

Answer 1

According to NFL Rule 5, Section 1, Article 4:

1) Quarterbacks, Punters and Kickers wear numbers 1-19.

2) Running Backs and Defensive Backs wear numbers 20-49

3) Centers wear 50-59 and if a number in that range is not available they may wear 60-79.

4) Guards and Tackles wear 60-79.

5) Wide Receivers wear 80-89 and if a number in that range is not available they may wear 10-19.

6) Tight Ends wear 80-89.

7) Defensive Linemen wear 60-79 and if a number in that range is not available they may wear 90-99.

8) Linebackers wear 50-59 and if a number in that range is not available they may wear 90-99.