Adding and Subtracting Tens worksheets for Grade 1 (Elementary School)

Problems such as 30 + 20 and 50 - 20 are handled by counting how many groups of ten there are. Three tens and two tens make five tens, and recounting this way produces the answer, an idea practiced through Calculation, Fill in the Blank and Word Problems.

The first error is answering 5 for 30 + 20, dropping the 0 in the ones place. The opposite also appears, with both zeros lined up to give 500. Whether the answer has two digits shows whether the child is still counting in groups of ten.