What exactly do you mean by math facts practice sheets? Upon googling I found this site: Free Math Worksheets which creates very basic worksheets for a variety of elementary school math practice.
Otherwise, this is probably not what you're looking for, but mathwords.com (in their words, "An interactive math dictionary with enough math words, math terms,
math formulas, pictures, diagrams, tables, and examples to satisfy your inner math geek.") has a lot of basic math definitions and facts for reference purposes, just in case that's what you're interested in.