In the process of familiarizing yourself with the information contained on this site, you will often come across the concept of "M number". The idea of the number "M", which was developed by Paul Magriel, first became widely known in the second book Harrington on Hold'em Volume II... The number "M" is very simple, despite its complex content.
The "M" number represents only the number of times a player has the initial pot in their stack. For example, if the blinds start at 10/20 and you get 1,500 in chips, that means your M starts at 50. Further in the game, as the blinds and bets rise, your M will shrink. Thus, M is a handy indicator of how freely and aggressively one should behave at one stage or another in a tournament. With a high M (early on) you are playing big pots on monstrous hands for real odds, in fact, just like you play most cash games. Once the M begins to contract, the quality of the hand itself rapidly becomes more important.
Why use M instead of the more familiar (at least for cash players) big blinds in your stack? A $ 1 - 2 no-limit player with $ 200 will say he has 100 big blinds, not an M of 66.7. One of the reasons for this is that you will have to push often and only take the starting pot in tournaments, something you never do when playing cash games. Each time you do this, you can simply add another M to your stack, which is great for getting your new M when playing at multiple tables. Another decisive reason is that, using the big blinds, you can view the extremely important moment of the bet, something that the cash game player should not even worry about. Here's a quick example that I usually give to novice players. Let's say you have a starting stack of 1,500 chips - at 100/200 blinds the M is 5. The blinds are raised to 100/200 with a 25 ante. What would your new M be like when the table is full?
The answer is slightly less than 3. Using the big blinds to gauge the aggressiveness of a game will give you the same 7.5 big blinds before and after betting. However, using M will show you that your effective stack has dropped incredibly compared to your initial sweat, and you need to start playing aggressively. (It is hardly a coincidence that players make most of the mistakes associated with M at this particular level of blinds - 100/200 with a bet of 25. Here the level increase is quite deceiving - adding a negligible amount of 25 seems small - and most players do not know how to adjust in time thus exiting the blinds too quickly.)
So what is the meaning of M? Someone might devote an entire book to this, but I will try to give here some guidelines on what strategy to play with different numbers of M. Try to remember that if the stack is large on the table, the maximum that you can lose with any hand is the number M of the next highest stack, and this must be borne in mind when making calculations.
If your M is over 20: This is a fairly deep stack for a tournament and in general you can play the same way as cash when the effective M numbers are as high. At Beginner to Intermediate levels, your M will often be above 20, and you should aim to play hands with good realistic odds, emphasize (strengthen) position, and control the pot on medium strength hands - all that you do in cash games.
If your M is from 11 to 20: in this situation, you can no longer speculate as much, and should concentrate mainly on hands that clearly have a high card. However, you still have room to maneuver, such as betting 3 and then folding pre-flop to bet 4, or firing up multiple barrels while bluffing after the flop. I usually try to be limited in this position, but I want to maneuver and try to get my stack back to the original 20+ position.
If M is between 6 and 10: this is what I call the "reboot zone". Here, the best tactic would be to play all-in against the one who opens the raises, in the hope of thereby provoking a fold and raising his own stack by a couple M. Such tactics are most effective when opposing the blind against the blind or the blind against the button / cutoff, i.e. situations where your opponent tends to open on a marginal hand and wants to fold (fold) if you are in a strong position. With a stack like that, you don't
you can afford to open a lot of hands, unless you intend to play for all your chips. Be economical in your actions, but look for an opportunity to play all the chips on your opponents' three bets.
If the M is 1 to 6: Here you are actually in push / fold mode. An open raise will waste too much stack to fold to a re-raise, so just bet all your chips and maximize the objectivity of the fold. People who are experienced in sit & go tournaments will have the advantage with a given M, as they know very well how to push / fold. Be aggressive if you can open an objective fold because you will either have to take some blinds or double up to get a chance. Estimate your own position to the minimum, even if the cards in your hand are better, as if your M is about 4, for example. It's often better to push on the button with crap like 59o than at gunpoint with something like A9o. Don't be afraid to go bankrupt, because very soon you will have to do something.
In my subsequent articles, I will go into detail about many other meanings of M, but for now, practice using it and feel the need for it. This concept is very important and can also be applied to multi-table tournament play. Learn to use it. You will be of great help against players at small buy-ins and you will begin to understand the thinking of more successful players at large buy-ins.
English 
Russian