Question about figuring out calories per serving in recipe?

when you make it, divide it into equal servings using 1/4 c measuring cup. I did it with a crock-pot oatmeal recipe that didn't list the quantity but said 6 servings. turned out to be 1/2 c per serving. also, calories are never exactly what the book says. it varies with product brand, fruit sugar content (which vares from fruit to fruit, each apple has a different caloric value even if they're the same type and weight). don't get too hung up on that .7 calorie... one serving may have 190 cal, the next may have 200 cal, it just depends. it's a guessing game, not matter how precise you think you're being.