This Problem Set is a part of the Lesson 2, Unit 3, Grade 3. In this lesson, students apply the commutative and distributive properties in the form of the "n + 1" strategy to solve unknown facts. For example, students relate 5 × 8 and 8 × 5 and then add one more group of 8 to solve 6 × 8 and, by extension, 8 × 6.