This is my favorite all time created number sense project. My kids love this project and look forward to the challenge of completing it. It is very open ended when it comes to solutions. It is also extremely flexible when it comes to time to complete, working alone or in groups and changing the 4 number combination used to complete it. 1489 is the "easiest" combination of numbers to ensure you complete all 100 questions. Please don`t let the word easy fool you. It is very challenging and only kids who work at this will get it fully completed. It will test their number sense, mental math abilities and order of operation skills to the limit. I love it because using a calculator actually makes the project harder because they will not remember what they punched in when an answer comes up on the calculator. I don`t allow calculators when they do it as I want to promote mental math skills. After they have completed this one, I challenge them with a much more difficult number combination and sometimes some of the answers are not possible but they work and work to try and find one. I put them in a large group and give them about 45 minutes to see what team works best together to come up with the most solutions. You will love this project because of the flexibility and the engagement your students will have. Looking for a great assignment for an evaluation. This is it!! I did not include an answer key because there are so many solutions to some of the questions I love the creativity the kids come up with. Please email with any questions if you are not sure how it works when you download it. ENJOY!!