Everytime I play golf, and that's going on 23 years now, I pick a ball. I'm not a GREAT golfer, but I can hold my own. But to me, a ball is a ball. Any ball I keep for more than 4 consecutive holes becomes a lucky ball, and that's all the separates a Noodle from a Mojo from a Pinnacle. So, after all this time, I finally tee'd up a ball and asked myself, "what do the numbers mean ?" I presumed it was for identifying purposes, but maybe they are sequential for a reason, similar to golf clubs...Nope.
"These single-digit numbers are simply there for identification purposes. If the members of a foursome are all playing a Titleist NXT ball, for example, one might play a ball with the number "1," another a "2," the third a "3," and the fourth a "4." This will allow the members to keep track of which ball belongs to each player.
These numbers usually appear just below the branding of the ball's name. All the balls from the same sleeve will have the same ID number.
A golf ball might also have a three-digit number on it, usually something in the 300s or 400s. If you notice such a number on a ball, this number is letting you know how many dimples are on the ball.
Another number that might appear on golf balls is the ball's compression rating. Until solid core balls drove the wound ball almost completely out of the market - beginning in the late 90s - compression rating was a big deal to golfers. A compression rating of 70 or 80 for a wound ball was regarded as an indicator that ball was a "ladies ball." A compression rating of 110 meant you had to swing very hard to make that ball work right (the he-man ball).
We know now that compression relates much more to feel than to distance. Solid, soft-core balls are a huge segment of the golf ball market now, and the compressions these day can be way down in the 30s or 40s (ranging up to 100 or so). When these low-compression balls first started appearing on the market, manufacturers felt there was still a stigma attached to low compression - i.e., that a low-compression ball would be viewed as a "ladies ball." And so numbers representing compression were dropped from most golf balls.
You'll still find them on some brands, however, and they are almost certain - these days - to be two digits.
So, to recap: A single-digit number is there for identification; a double-digit number most likely represents compression; a triple-digit number most likely represents the number of dimples."