This Problem Set is a part of the Lesson 22, Unit 4, Grade 2. In this lesson, students apply the associative property to add up to four two-digit addends with totals within 200. They use the associative property, to add numbers in an order that is easiest to compute, for example, when solving 24 + 36 + 55, a student adding ones may make a ten first with 4 and 6.
