The basic ‘M’ score assumes a full table of 9 or 10 players. When there are less players the blinds will come around faster – and so your M is adjusted to compensate. Dividing your current M by the ratio of players at the table is know as ‘Effective M’. For example, you have 5000 chips with 5 players left – the blinds total 500, your M now equals 5000/500 = 10, however only 50% of a full table are playing so you divide by 2 for an effective M of 5.