In this section

Historical Rules · 29 September 2017

Rule 208.4

Official source text from the 29 September 2017 Rules release

Permalink

Effects that set a creature’s power and/or toughness to specific values may refer to that creature’s “base power,” “base toughness,” or “base power and toughness.” Other continuous effects may further modify the creature’s power and toughness. See rule 613, “Interaction of Continuous Effects.”

Find this number in the current Rules