How di o do this one?

Question

6!12

____

8!13!

Answer 1

! means the problem is a factorial. Factorials are where you multiply the number by itself minus 1, until you hit 1. If you have X! you would do X(X-1)(X-2)(X-3)... until you hit (X-Y)=1, where you stop.

As such this problem could be written as:

6(5(4(3(2(1)(12)

_____________

8(7(6(5(4(3(2(1) x 13(12(11(10(9(8(7(6(5(4(3(2(1)

Then you simply cancel out where you can. Resulting in:

1

____

8(7) x (13(11(10(9(8(7(6(5(4(3(2)

Which comes out to be 1/29059430400

Answer 2

Here is a reminder about what factorials are:

http://en.wikipedia.org/wiki/Factorial

Answer 3

Remember that any number with an ! attached to it means you multiply that number by any preceding number all the way back to 1.

Therefore:

6! = 6*5*4*3*2*1 = 720

8! = 8*7*6*5*4*3*2*1 = 40,320

13! = 13*12*11*10*9*8*7*6*5*4*3*2*1 = 6,227,020,800

So you have

(720*12) / (40,320*6,227,020,800)

(8,640) / (40,320*6,227,020,800)

0.00000000034412 = 3.4 X 10^-11

You might also try simplifying this one before you start.

Because you know that 8! is 8*7*6*5*4*3*2*1 it also equals 8*7*6!

You can now cancel the 6! in the denominator with the 6! in the numerator to get:

12 / (8*7*13!)  

12 / (56*13!)

Either way you will still get 3.4 X 10^-11