I use this is my classroom because we follow the Common Core Standards. I use it as a Problem of the Day, but it can be used as task cards, homework, or formative assessments.
I have included an answer key for each problem. There are 6 problems in total.
This is for a 3rd grade classroom, but could be used as enrichment for 2nd grade. It matches Common Core Standard 3.OA.9 (arithmetic patterns and properties of operations)