This Application Problem is a part of the Lesson 14, Unit 1, Grade 3. Jackie buys 21 pizzas for a party. She places 3 pizzas on each table. How many tables are there? This problem reviews division from Lesson 13 where the unknown is the number of groups. In preparation for today's lesson, the teacher might choose to have students solve by skip-counting to add units until they reach the total of 21.