You’ll find that the number of ways to shuffle a card pack (52!) is about 8 × 10⁶⁷, so even if your RNG returns 64 bits, you can’t use a single call. Also, you

You’ll find that the number of ways to shuffle a card pack (52!) is about 8 × 10⁶⁷, so even if your RNG returns 64 bits, you can’t use a single call. Also, you’ll have to make sure you pick each permutation is picked with equal probability. random() % factorial(52) likely won’t work because your RNG won’t return integers in a range k × 52! for some k > 1 (https://stackoverflow.com/questions/10984974/why-do-people-say-there-is-modulo-bias-when-using-a-random-number-generator https://stackoverflow.com/questions/10984974/why-do-people-s...)