What is four twentyoneths simplified

4/21 cannot be reduced any more than it is 

4/21 cannot be simplified any more due to the fact that while 4/21 can be divided by other numbers, both numbers have to be divided by both the same number. Since there is no number that can go into both 4 and 21, 4/21 is the simplest it can get

Here are the answers to the ones that i could see.