Your spermy friends will survive for 6 days.
Her oeuf, once released, has 24 hours to meet a keen sperm, before it falls out her bum or something odd like that.
Above are correct, with the idea that the egg is released circa 14 days before her period starts….
Ergo, you can only really fall pregnant by having sexy sex on 7 days of the cycle…..
Unless you’re 16 and met the guy at a party – then it can happen at any time, with 3 forms of contraception….it seems….
DrP