Of the many numbers a person sees every day, sometimes a person sees a number that has personal meaning or has an emotional significance. Because it is different from the other numbers in that way, a mental note is made.

That mental note makes it more likely to be remembered as being seen. Other numbers that are seen are not remembered as being seen.

Perhaps this is the story:

Your day of birth is the 25th. That probably got you started remembering it when you saw the number 25.

When you started wondering why you saw the number 25 so often, the number became emotionally significant — even though you saw many other numbers, just didn't remember seeing those others.

Now, with both a personal meaning and an emotional significance, you started remembering it more often when you saw the number 25.

The more you remembered seeing the number 25, the more you assumed there must be special significance and the more emotional energy was invested.

So you started seeing 25 even more. And it progressed to where you now see the "2" and "5" separately and reversed within other numbers. (The digits "2" and "5" are 20% of all the digits available, so you are prone to remember the seeing of a fifth of all numbers that occur in your environment.)

And the more you see the digits "2" and "5", even when they aren't together as one number "25", the more desperate becomes the manufactured need to know what it means.

What it means is that you remember it whenever you see your day of birth or parts of your day of birth. See Why You Start Seeing Certain Numbers Again and Again and also Why People See Certain Numbers All the Time for more information.