Math formula of picking bridal party

Wow, I didn't know there was a rule towards choosing the number of bridesmaids;

"...some wedding experts agree that a good rule of thumb is to have one groomsman and one corresponding bridesmaid for every 50 guests,"source

With 300 guest, that would be a party of 6 bridesmaids and 6 groomsmen which is perfectly what we wanted (5 bridesmaids and 1 maid of honour plus the corresponding groomsmen and best man)