The question is actually not so specific. Two possible
thought it meant.
1. If you meant the volume of powder cement to fill 1mmm
then the answere is from 29 to 30 bags.
2. If you meant no of bags to use for a mix to form a 1mmm
concrete, then the answer is nearly 8 bags. The
rest of the volume is for san and gravel.
Maybe it helps. thanks.