This printable contains examples and practice questions that look at six different ways to add two 4-digit numbers. The methods that are included are: Friendly Number and Compensation, Counting On, Criss-Cross, Front-End, Traditional, and Expanded Form. The intent is to expose students to various ways of thinking (mental math) about addition of numbers in the thousands. Go through each example together as a class. Do one or two questions together. Have the students try the rest on their own. Either check the answers together or have them practice their calculator skills by punching the numbers in themselves to see if they were correct.