"For as Jonas was three days and three nights in the whale's belly; so shall the Son of man be three days and three nights in the heart of the earth." - Matthew 12:40
Now you might be better at mathematics than I (this is not saying much), but even you can not put three days and nights (even it you switch the order to the more Jewish "nights and days") between a Good Friday crucifixion and an Easter Sunday resurrection.
The Catholic tradition of Jesus dying on a Friday can be largely blamed on a misunderstanding of the word "sabbath". "Six days shall work be done: but the seventh day is the sabbath of rest, an holy convocation; ye shall do no work therein: it is the sabbath of the LORD in all your dwellings." - Leviticus 23:3
If you looked at this passage in Mark chapter fifteen, assuming that the "sabbath" meant "Saturday", a burial on Friday would be the only logical conclusion: "And now when the even was come, because it was the preparation, that is, the day before the sabbath, Joseph of Arimathaea, an honourable counsellor, which also waited for the kingdom of God, came, and went in boldly unto Pilate, and craved the body of Jesus." - Mark 15:42-43
But what if your idea of the sabbath always meaning the seventh day, was incorrect? What if there was more than one type of sabbath in the Bible? What if you thought of "sabbath" as meaning a "holy day when no work was allowed"? There are other sabbaths, relating to the Hebrew Feasts, described in Leviticus 23:4-44. While the Passover is not a sabbath day when no work is allowed to be done ("an holy convocation: ye shall do no servile work therein"), there are days besides Saturday alone that are sabbath days.
