1 + 6 - 5 + 9 / 9 =3
Basically, quantum mechanica talks about the improbability of things, no matter how unlikely they are. One of them is the assumption that waves are also particles, and particles also waves on a very small (sub-atomic) scale. This means that electrons do not go in an eclipse around their core like scientists assumed before they found this. This on their turn means it's impossible to determine the exact location and speed of the electrons unless you're actively studying it at that very moment, and even then you can't see the exact location and speed at the same time. This problem can only be solved by assuming that the electons of a single atom are at all possible locations it could possibly be at the same time unless you defined the exact location, because otherwise calculations would end up being answered by infinity anyways. The same would go for the speed.
Got it so far?