This Application Problem is a part of the Lesson 26, Unit 2, Grade 1. Ruben has 18 toy cars. His car carrier holds 10 toy cars. If Ruben's carrier is full, how many cars are in the carrier, and how many cars are outside of the carrier? This problem enables students to continue considering situations with missing parts where the context presents a grouping of 10. This grouping of 10 leads into today's lesson during which students focus on ten as a unit.