Let's see he was in the tomb when it was night on Friday and when it was night on Saturday and when it was night on Sunday.
According to my calculator, that's 3.
You better calculate again. How do you figure he was in the tomb on Sunday night when the tomb was empty on Sunday morning?
If you are going to count the predawn hours of Sunday as Sunday night - then when was Saturday night? You can't split one night into two and call it both Saturday night and Sunday night. It's one or the other.
He was crucified on Friday afternoon. Friday is the first day. Friday night is first night. Saturday is the second day and Saturday night is the second night. Sunday is the third day. Where is the third night? Not Sunday night because he was already in the tomb.