The hockey jersey number thread got me thinking about basketball jersey numbers. I notice that NBA teams rarely use 6, 7, 8 or 9 in either digit of double-digit numbers. Both digits seem to be limited from 0 through 5. For example, you never see a number 27, but you often see a 22. Occasionally, you’ll see this “rule” violated, but very rarely. For single digit numbers, this limitation doesn’t seem to exist.
I don’t know if it’s an actual rule, but there has been a preference for numbers that can be easily represented through hand signals by the referees. The ref can represent any single digit number by holding up that many fingers, and he/she can signal a double-digit number (with each digit lower than five) by holding the hands up separately, or one at a time. A two-digit number where one digit, or both, is greater than five could get confusing.
But that said, there have been more of those numbers in recent years. Dennis Rodman wore 91 with the Bulls, and then was 73 with the Lakers and 70 with the Mavericks. Ron Artest was 91 (tribute to Rodman) at the end of his time with the Pacers, then wore 93 with the Kings, 96 with the Rockets, and is now 37 (tribute to Michael Jackson, he says) with the Lakers. I’m not sure there are a lot of other examples, but it’s not totally verboten, at least.
Okay, one other example: Rasheed Wallace wore 36 for his one game with the Hawks, and for some of his time with the Pistons.
This page features legal jersey numbers for FIBA (Olympic and other international competition), NCAA, and U.S. pro (NBA/WNBA) basketball. FIBA has a very limited range (twelve legal numbers, twelve players per team, so no retiring of jerseys possible). As already stated, college players are limited to combinations of digits in the 0-5 range. The WNBA is a bit more lenient, while the NBA apparently has no restrictions (although I’d assume triple or quadruple digits are forbidden).