A tip for you, stay away from the middle of and the inner walls of the corridors as much as possible, since those are where Cleany Clean usually stays close to. It's better to stay close to the outer walls of the corridors where he is less likely to sweep you. You cannot avoid him in narrow hallways, however. Oh, and make sure you have found the neodymium magnet and have a personal handheld calculator with you (real life, not virtual in game) before you solve the 10th notebook. When you solve the 10th notebook, lure Viktor as far away from the 1st classroom where you solved the 1st notebook as you can, then immediately hurry back to the first classroom top speed without staining Viktor's shirt along the way. When you reach the first classroom, lock the door behind you with the neodymium magnet, you'll know why eventually, I won't spoil the reason why. Hopefully you've practiced memorizing the map in little puss mode, cuz that's what it's there for.