This Problem Set is a part of the Lesson 2, Unit 5, Grade 6. Understand that we can compose 10 like base-ten units as a base-ten unit of higher value (e.g., 10 tenths is 1 one) when adding decimals. Understand that adding and subtracting decimals requires combining digits that represent like base-ten units. Add and subtract decimals by writing the calculations vertically with digits in the same places aligned.