This is a sample of an activity called "Ransom note." Before giving this activity to my students, I use a ransom note generator to create a letter explaining that a number has been stolen. Students have to determine which number has been stolen based on the clues provided. I usually try to spiral other skills, such as addition or subtraction, in this activity. My students really enjoy this, especially when there's music pumping in the background. Feel free to modify this activity to fit your students' needs.