...or B, also try this in Excel.
If you have a list of numbers and you want to select one at random follow these simple steps;
Enter a list of numbers in column A
Now enter the formula below in the cell you want the random number returned.
=INDEX($A:$A,RANDBETWEEN(1,COUNTA($A:$A)),1)
This will pick a number at random from your list in column A. It will also be dynamic in that when/if you add/remove numbers from the list they will automatically be included/excluded.
S2