Hi all! Greetings from Switzerland!  
I'm new in this forum and I hope that I'm posting my question in the right section!  
I have a big problem and I hope that someone can help me with it. 
As I'm very new to the subject of composing and orchestration, I would like to know how do I calculate the strings in a symphony orchestra ? 
What I mean is... if the scores for example says this: 2-2-2-2 -4-2-3 (Richard Wagner Symphony No 2) or 2-2-2-2-2-2 (Franz Schubert Symphony No. 3)  how do I know how many strings I will need to perform this piece ? 
Thank you for your help!