How often are extra queens required?

According to Wikipedia, promotion occurs in about 1.5% of games and in about 97% of the cases it's a promotion to a queen.

I'm wondering, does anyone have any statistics on how often, out of those cases, did the promoting player still have the 'original' queen on the board? In other words, many chess sets have 4 queens - how often are those actually required? 

I guess an extra queen is not necessary.

Almost allways the original queen was already removed, or at least one of the rooks, that you can turn upside down with no problem.

If you still have both rooks and the original queen when about to promote a pawn... well, the situation is probably terrible to your opponent and they usually resign before that anyway.

I wrote probably in bold to avoid people posting here weird positions in which someone has both rooks and 2 queens and yet doesn't have an easy victory.

This is possible, but rare, that was my point.

It seems so low that only 1.5% of games have a promotion... well I guess most resign when promotion is imminent.

It's relatively rare, but I've made use of my set's extra queens before.

There's also the situation when promoted queen is immediately taken off the board, the promoting side winning a piece, so there is really no need to put an extra quuen on the board.

What's the question?

I can't believe only 1.5% of chess games have a promotion. Perhaps that number is only for recorded titled player games and not the general chess population. I would say more realisticly that promotions happen perhaps 15% of the games and that they just put the decimal place in the wrong spot.

Well they must have used a database and crunched the numbers.  There's only 1 database I know of that has a bunch of online games from amateurs.  Likely it was from a database of strong tournament players in which case 1.5% makes a lot of sense.

How does an OTB tournament director handle a situation where extra queens are required?  How many pieces are you allowed to bring?

Well you can use queens from a different set if you don't have any extra of your own, but that's more of a player problem not a TD problem.  If there are no extra queens anywhere I suppose the TD would have to let you use an upside down rook or some such thing (although it's hard to imagine a situation where there are no extra queens).

How many pieces are you allowed to bring?  You can bring all the extra pieces you want lol.  If you mean how many underpormotions are allowed, each player is allowed a maximum of 8.

So yeah, seeing as that's all commen sense crap I was wondering what you question was

Oh, ok.

I mean there's usually someone done fairly quickly and I'd just grab on of theirs.  Also the TD whose tournaments I most often go usually has a few sets on display for sale (just cheap tournament starter stuff).

If some stupid kid decided to get 6 knights I don't know what people would do lol.

A month ago I purchased 12 complete chess sets for my group that I teach. I made sure that all the sets came with an extra queen.

Beginners do get extra queens in their games, I have noticed. In just a 30 games in a session 6 of the players will Queen a pawn. Mainly because they don't know how to stop it yet. 

It could be because I used to train them to play Pawns vs Pawns and the objective was to get a pawn to the eight rank, and that would be a win.

The Wikipedia article I linked got the figure from the "2006 ChessBase database of 3,200,000 games (many grandmaster- and master-level)" - so the amount of promotions does seems low because strong players typically resign when they see that they cannot stop their opponent from promoting. 

I was just curious about how many of those games had a queen of the same colour already on the board - but I guess the only way to know is to get access to the database myself.

Extra queens are required for me to win about 50% of my games. Unfortunately I'm not usually in a position to acquire one :-)

The figure of promotions only occurring in 1.5% of games looks like nonsense. I suspect what is meant is a player having a second queen in 1.5% of games.

When I look at my database of 4.2 million games (mostly master) I see over 1% of games have one or other side having 2 queens at some time. Surely times when queening occurs after an exchange of queens must be much more common, from experience?

[Filtering for high rated players does not reduce this fraction much].

Thanks a bunch, Elroch, that's exactly the kind of statistic I was curious about! 

Extra Queens are not "required" but "acquired". Coming to part B - how many times?

How many passed pawns can be "Queenable"? that many times. 

How do you underpromote if/when there is no spared knight or bishop available?

The upside down rook as queen is not permissible in official tournaments. A second queen has to be borrowed from another set if necessary.

That depends on which rules you are using.  According to USCF rule 8F7:

"It is common practice, however, to play using an upside-down rook for a second queen.  In the absence of the player's announcement to the contrary, an upside-down rook shall be considered a queen."

And why not?  People generally know what it means, it doesn't look confusingly like a normal rook, and sometimes a second queen isn't at hand but a rook is.  And there are very few games where a promotion occurs without a rook OR queen captured.

The record of numbers of queens on The board is 9. I can try to find The source later if wanted. Though it was 9 queens in totalt, black and White together.