Question about 9v battery substitutes

[Jumbosize]

Hello, I have a quick question regarding batteries and voltages. Does the voltage add up if batteries are used in series with one another? If so, could I theoretically use three 3v coin cell batteries in place of a 9v battery? Would there be any side affects from this?  I'm trying to build a simple boost pedal that I want to see how small of an enclosure I can squeeze it into just for grins.

[Tony Forestiere]

Yep. Batteries in series=additive voltage with the same current potential; parallel=additive current potential with the same voltage.