Seven
Lucky for you (as is the case with many of the lower-stroke kanji), this kanji is the same as the radical you've already learned. The radical that makes up this kanji is seven and the kanji (which is exactly the same) is also seven. So, if you know the radical, you know the meaning of the kanji as well.
Make sure you know your radicals well and you'll be A-Okay on this one!
しち
なな, なの
None
You know this kanji means Seven, so let's use that to remember the reading too. Seven is a lucky number, usually, but this time it wasn't so good. Seven percent is all she got on her test after she cheated (しち) on it.
How unbelievable is it that someone got seven percent on a test, especially if you try to cheat? Imagine the girl you loathe the most from school, and imagine her cheating on the test (it's important it's a girl, because of the "she" part in she cheated (しち). Then, imagine your happiness when she's super upset about getting seven percent on it. Serves her right, obviously.