# Find volume of sample such that it contains 100ng of DNA

Im struggling with the maths of concentrationsand volumes and things..Ill give the question, then my thoughts on it:

A DNA trimer strand, ab, has moleuclar weight of $9309ng/\mu mol$. I#m designing a page gel to test the weights of few, but i only need to do it with this one to understand the maths of it. I need to find the volume that contains 100ng of the DNA trimer strand. It has a concentration of $876.36 ng/\mu L$ and a volume of $20\mu L$.

So, what I did is: in the sample we have $876.36 ng/\mu L *20\mu L=17527.2ng$. For just $100ng$ of this, we divide $17527.2ng$ by 100 to find the factor, and we divide the volume by the same amount - which gives us $0.114 \mu L$ of the sample. Is this right? It seems very little to me, but Im still new to this lab calculation stuff and am constantly surprised by it.

Thanks!