Question 945181
<pre>`
30 Choose 5 = 30C5 = 142506

Start with 30, then multiply by 1 less, then by 1 more less, etc.
until you have 5 factors on top, {{{30*29*28*27*25.  That's the
numerators.  Then for the denominator, start with 5 and multiply 
by 1 less, then 1 more less, etc until you also have 5 factors 
on the bottom.

{{{(30*29*28*27*26)/(5*4*3*2*1)}}}

Then have a hay-day of canceling

Cancel the 5 into the 30, get 6.
Cancel the 4 into the 28, getting 7.
Cancel the 3 into the 29, getting 9.
Cancel the 2 into the 26, getting 13.

  6     7  9  13
{{{(cross(30)*29*cross(28)*cross(27)*cross(26))/(cross(5)*cross(4)*cross(3)*cross(2)*1)}}}
   1  1 1  1
 
So it's 6×29×7×9×13 = 142506

If you have a TI graphing calculator, you can do this

type 30
press MATH
Press the left arrow key <-
Press 
3          (Should see 30 nCr
type 5     (Should see 30 nCr 5
press ENTER

See 142506 

Edwin</pre>