This is a great activity that I've used both as a warm-up as well as a class activity that promotes discussion regarding strategies for finding the percent of a number. The problems selected are connected, so it is designed to encourage follow-up questions about how they used certain problems to solve others.

It can be an individual activity or students can work in pairs. I like for them to have 2 minutes for the first round, and then answer the others in another color pen for about 5 more minutes. Please adjust time based on your knowledge of your students, but it is designed as a two-part activity.