How many positions are there in the biggest chess endgame tablebase?

I've been googling this question. Google comes up with all the wrong answers. It tells me the database has been solved for 7 pieces on the board and that it's about 1 Terabyte of data. Other answers that come up are how many positions there are in the opening after one, two three moves etc.

I just want to know, with the latest endgame databases (why do we call them tablebases?), how many positions are stored in that ~1TB of data?

You could try messaging the developers of one of those endgame tablebases to see if they know.

or you can count them :)

if anyone is intresting to join my simul send me private message

We can calculate it approximately.

Let's look first at the number of ways of putting 7 pieces including a white and black king and no other kings on a chessboard without worrying about whether the position is legal.

First place the two kings: 64*63 ways to do that.

Now choose 5 other squares for the remaining 5 pieces: 6261605958/120 ways. (We divide by 120 because there are 120 orderings of 5 squares and the ordering doesn't matter. The number can be called "62 choose 5".)

Now choose which of the 10 remaining possible pieces (black pawn, white bishop, etc) can be placed on those 5 other squares. This is 10^5 or 100000.

So the total number of ways of placing the white king, the black king and 5 other pieces on a chessboard is:

64636261605958*100000/120
=2609108006400000
or about 2.609 * 10^15

Multiply by 2 because either side may be to move:
5.218*10^15

Now we must estimate the number of those positions which are illegal. For example, the kings must not be together, any pawns must not be on the first or last rank, and some other considerations. This is licking my finger and sticking it in the air, but let's guess that about 90% will be legal positions. 90% of 5.218*10^15 is about

4.7*10^15

You might want to divide that number by 2 if you want to regard a position which is the same but with White and Black reversed as the same position.

I don't know how you google, because I found it in the 4th search result.

The 7 piece database that Lichess uses (created by Bojun Guo aka noobpwnftw and Ronald de Man aka syzygy) has 423,836,835,667,331 positions.

https://lichess.org/blog/W3WeMyQAACQAdfAL/7-piece-syzygy-tablebases-are-complete