probability of getting a royalflush

Royal flush: Five highest cards of the same suit. Ace, King, Queen, Jack, Ten:

Number of possible 5-card hands: 4. Chance:52C5=2,598,960. Or 4 chances in 2,598,960=1 chance in 649,740.

You need to specify what that means.

A royal flush is ten- jack- queen- king- ace   ALL of the same suit. (so there are 4 royal flushes in each 52 card deck)     Are you asking about being dealt this with only 5 cards?   Or do you discard and get some more?

4 x 1/52 x 1/51 x 1/50 x 1/49 x 1/48 =  1:77,968,800  (?)    if you do not get to 'draw' any additional cards

4 x 1/52 x 1/51 x 1/50 x 1/49 x 1/48 =  1:77,968,800  (?)    if you do not get to 'draw' any additional cards

I just guessed....the susequent answer is correct ....  SEE:

https://en.wikipedia.org/wiki/Poker_probability

There are 52C5 ways to draw 5 card. Only 4 of those are royal flushes.

So

Prob is  4/  52C5

nCr(52,5) = 2598960

So it is  4/2598960

2598960/4 = 649740

So it is  1/649740

This is assuming you pick up 5 cards and they are 10, J, Q, K, A all of the same suite BUT the order they are picked up in is NOT relevant.