You'll also want people to RSVP so you have a head count for the caterer. If, on the other hand, your rehearsal dinner will be fairly low-key or small (think: a party at a restaurant or an intimate gathering at your future in-laws' home) then you don't need to be as official with your invitations.
The exact nutritional value of an orange depends on its variety. According to the U.S. Department of Agriculture, a standard-sized navel orange contains 69 calories, 17.6 grams of carbohydrates and 11.9 grams of sugar.
A serving of 100 grams of oranges will have 47 calories. An ounce of oranges will have 13 calories. In half a cup of canned mandarin oranges in light syrup that weighs 4.3 ounces, there are 80 calories. In a can of mandarin oranges in light syrup that weighs 11 ounces, there are 205 calories. In a cup of orange juice that weighs 248 grams there are 111 calories.