Help with Insulin/syringe math!!!

Hi all!
Am desperate for some help. A particular questions has been plaguing my fellow classmates and me. Our teachers presented us with a question in class that we can't seem to make sense of. The question was:
If you were to draw up 5 units of U50 insulin in a U100 syringe, how much would you draw up?
Now, I know that technically you should only draw up insulin with a syringe calibrated to the same concentration of insulin (use a U50 syringe with U50 insulin, U100 syringe with U100 insulin, etc.). Ignoring that fact, how much would you draw up? I was so confused by the answer that I didn't even bother to write it down, so I don't remember what the answer was. Can anyone answer, and explain that answer, to me? 

Oct 24, '12From what I could find online, u 50 is a 1/2 strength insulin. So 5 units of u 50 would be 2.5 units of u 100, at least that's what I'm thinking. Not sure if its right. I haven't run into having to draw up u50 insulins. We have u100 on our unit.

Oct 31, '12U50 insulin contains 50 units in each mL, and so 5 units would be 0.1mL.
U100 syringe is calibrated such that each unit equals 0.001mL (100 units in 1mL). You need to draw up 0.1mL, which would be the 10unit mark on this syringe.
Or, as previous poster said, U50 insulin is half strength of U100 insulin. So, you'll need twice the amount  so you need to draw up to 10unit mark instead of 5unit mark.