I had the unbelievable experience of drawing a seven-card straight flush while playing with five other players with one deck. The hand started with the ace of spades and ended with the seven of spades (all spades). Has anyone calculated the odds of that occurring? PS. The hand was not dealt in order. PPS. Unfortunately, it was nickel-dime.
Was it seven cards drawn from the deck with no replacements? There are 52 choose 7 different 7-card combinations from a standard deck. In one suit, there are 8 different 7-card straights possible. So 32 different seven-card straight flushes are possible.
That makes the odds of drawing this mostly 32 / 52C7 for each hand (not quite, because hands drawn in a single round aren't independent, but it's pretty close). That's 2.39 x 10^-7 or close to 1 in 4.2 million.