I just learned that in math there are these things called factorials and the symbol for it is an exclamation point (!)?????? Which I think is so awesome.
factorials are used in problems like this: You have 5 shirts and 3 pants. How many combinations can you make? And the answer is 15 (5*3=15). You do that with harder problems too but then its easier to use factorials which have a calculator button since the numbers will be so big.
Like, how many different ways can you arrange 9 people in 1 row? You have nine variables that can be arranged 9 different ways each. So you could do 1*2*3*4*5*6*7*8*9 = 362880 or you can use factorials! (that exclamation point was used as an actual punctuation mark lol). The format is nPk where n is the number of things and k is how many different ways can you arrange them. To solve the problem it’s nPk = (n!)/(n-k!).
n=9 and k=9 in this problem. So 9P9 = (9!)/(9-9!) = 9!/0!
Now you might be saying, “wait you can’t have a zero in the denominator ‘ which is usually true but the exception is factorials because 0!=1. This is because a good way of thinking of factorials is asking yourself, “how many combinations can I have?” You have 3 numbers in the number 3 (1,2,3) which can be arranged 6 different ways. So 3! = 6, there are six ways for the factorial to be. And 0 only has 1 combination because nothing is always gonna be...nothing. There’s only 1 way for it to be. So that’s why 0! = 1.
SO 9!/0! = 9!/1. When I put that in my calculator I get 362880! Which is what I got earlier but this way there are less numbers to get mixed up when inputting them into the calculator. (On my graphing calculator, to get the factorials symbol, I click the “math” button, then go to the “Prob” (probability) section, and then hit “4″)
Anyway, this was my math rant for today!!!!!!!
