standard_description: Use variables to represent numbers and write expressions when solving a real-world or mathematical problem; understand that a variable can represent an unknown number, or, depending on the purpose at hand, any number in a specified set.
problem_activity: Task
What is the last digit of $7^{2011}$?  Explain.
What are the last  two  digits of $7^{2011}$?  Explain.


aligns: no