Magic Squares are great review activities for students to apply what they have learned throughout the Unit. The best part is that they are self-checking! Once students have matched up the question to the correct answer, they simply add up the numbers in each column/row to see what number they equal. If all columns and rows are the same, then they have found the Magic Number, and has correctly answered all questions.
I use these in my class all the time as extensions for my quick-to-finish students. I have several different ones laminated (or put in page protectors), and allow students to use dry erase markers to complete whenever time allows. This is always a hit for students, who love to complete Magic Squares for the current, as well as previous units.