This Problem Set is a part of the Lesson 5, Unit 5, Grade 2. In this lesson, students apply their knowledge of number decomposition to strategies to add numbers within 1,000. They use number bonds to decompose larger numbers, so that they can add multiples of 10 by making 100. For example, when solving 320 + 290, they can break 320 into 10 and 310 to make 310 + 300 = 610.