107.1c

f a rule or ability instructs a player to choose "any number," that player may choose any positive number or zero,

Slaughter the Strong. You can choose zero creature (and sacrife all creatures you control).

unless something (such as damage or counters) is being divided or distributed among "any number" of players and/or objects. In that case, a nonzero number of players and/or objects must be chosen if possible.

Butcher Orgg. If you choose to use the ability to divide up the damage (and there is at least one point of damage to be assigned), you must choose at least one creature or the defending player, and can’t choose more total creatures and players than the amount of damage being assigned (minimum 1 point per player or creature).