Calendar Math is great...and I use this version for my middle school math students. My kids keep it in my room on a shelf, and grab it as soon as they walk in the door. It only takes a few minutes, and is a good starter activity. I print this back to back and give the kids a new one each week.
The PEMDAS (Order of Operations) problems can be a lot of fun, and challenging too. I tell the kids they need to use all 6 numbers (once and only once) and can use any combination of PEMDAS with as many sets of parentheses as needed. Any of the numbers can be used as an exponent. If we can't get the exact answer, we try to get as close as possible.
Also, I use the number 180 as my number of days in the school year just because it is a "friendlier" number to use than our actual number of days. If you'd prefer a different number, let me know in your review, and I will get you a different copy. Thanks!