"Chappie" debuted at No. 1 with an estimated $13.3 million in the U.S. and Canada during a slow box office weekend, while the Vince Vaughn comedy "Unfinished Business" opened at No. 10 with a mere $4.8 million.
Last week's top film, "Focus," fell 46 percent in ticket sales and finished second with about $10 million. Fox Searchlight's "The Second Best Exotic Marigold Hotel" came in at third with a solid $8.6 million start.