Thank you for all the kind replies pertinant to my question. My vet (where it did come from) did finally call me back after I left voicemails later that day. Which was very nice of her, since she was on a 3 day vacation. My daughter made the error in picking up the larger box at close of business that day. She has a large breed dog, so I don't think she mentioned it was for yorkies

Either or..the correct dosage was .125 ml for under 5lbs and .25 ml for 5.1-10 lbs, per my vet. She also said it was wiser to get the larger amount since I cut my costs significantly LOL. She said it is simply a marketing technique to buy smaller amounts for smaller dogs. Your math (KJC) was correct. Thanks again. I usually use advantage, but opted to switch after hearing many good reviews from my vet and others. I just use a monthly protection and it keeps me from having to use the heart guard as well. One sort of multi medicine. Anyway first month of use and so far so good. Thank you again for all the kind reviews that answered my question

I don't advocate anyone else doing that, check with your vet!