I suggest you look into acquiring a good contest logging program. It will generate the correct sequence numbers for you so you don't have to keep track of them. Back when we had to do all that manually, it was easy to make a mistake. For many years I've used N1MM logger for contests. When the contest is over, if you want to submit your log to the contest sponsor, it will generate your log in Cabrillo format, which is what most contest sponsors want. If will also output your log in ADIF format, which is good for importing into your daily log program if you use one. N1MM logger is enormously complex, but the documentation is very good and there's an N1MM group on groups.io where you can get answers to your questions. Once you master the basic operation of N1MM, it's very simple to use. And, you can learn it's features and setup prior to actually being in a contest. It's free and available via download. There are other contest logging programs of course, some free, some for a fee.
73, K8AC