Someone ought to check my working, but
A/
You start with 1 ace. You can see 2 cards. There are 50 cards you can’t see. There are 3 hidden aces. There are 47 hidden non-aces. There are 16 cards in other players’ hands. There are 34 cards in the deck.
So what are the chances that none of the aces are in the 16 cards?
(47! / (16! 31!)) / (50! / (16! 34!))
(34 × 33 × 32)/(50 × 49 × 48) = 30.5%
ie There is about a 69.5% that one of the eight other players has at least one ace.
B/
There’s an ace in the flop.
Now there are 47 cards unseen. There are 2 hidden aces. There are 45 hidden non-aces. There are 16 cards in other players’ hands. There are 31 cards in the deck.
(45! / (16! 29!)) / (47! / (16! 31!))
= (31 × 30)/(47 × 46 )
There’s a 43% chance that there are no aces in the 16 cards: ie, there is a 57% chance that one of the other players has an ace.
C/
There’s one ace altogether in the window cards.
45 cards unseen, 2 hidden aces, 43 hidden non-aces, 16 cards in the other hands, 29 cards in the deck.
(43!/(16!27!))/(45!/(16!/29!) = 29 × 28 / (45 × 44)
There’s 41% chance that there are no aces in the 16 cards, and a 59% chance that one of the other players has an ace. Note that this is a higher % than in scenario B, because we have revealed two more non-aces.
So how to estimate this on the fly?
It might be simpler to just remember a few dozen stats than try to do these calculations in your head during the few seconds of thinking time you have during a game of poker. But you might think this way:
A/ Three aces, about two thirds of the cards are in the deck. Any given ace has about a two thirds chance of being in the deck, so the chance of them all being in there are 2/3 ^3, ie 8/27 ,about 30%, so there’s a 70% chance one of the enemy has an ace.
B/ Two aces now, still about two thirds of the cards are in the deck, so 2/3 ^ 2 = 4/9, 44%, about 56% chance someone else holds an ace.
C/ Same as above, except the total number of cards has gone down by about a twentieth, so the chance of each ace has gone down by a twentieth, so the chance of both aces has gone down by a tenth, about 40%, so 60% chance someone else is holding an ace.