Mathematica needs you! Add, subtract, divide and multiply your way to victory. Meet the Karate Cats and practice spelling, grammar and punctuation as you chop, kick and smash the challenges. Join ...

The apostrophe can be used to show who things belong to. If an item belongs to something, the apostrophe shows us who, by sitting at the end of the noun. If that noun doesn't end in s, the apostrophe ...