Hi Nelissa, thank you for reading my rant! You can let your friend know that it takes about 1,500 lemons to make 16 ounces of essential oil. The average bottle of essential oil comes in 15ml and there are about 20 drops per 1ml. Hope they are good at math! I think I gave them a pretty good start, its a fun equation. Which might surprise you on the answer to that. Let me know what they come up with and we can compare, contrast, agree or disagree! :P