How do you pronounce the apostrophe in a formula?

[roesmets]

Sorry to bother you all with a trivial question. I'm a Belgian teacher and I'm struggling because I don't know how to read a formula in English. How do you pronounce the apostrophe in for example v'. In French we say 'prime'Can anyone help?

 

[ZapperZ]

You say "v prime".

Zz.

 

[roesmets]

Thank you very much

 

[Meir Achuz]

The pronunciation is a bit different in English.
The i in prime is pronounced like the English word eye.