Here is a great way to get the most from your cardstock!

Trading cards are 2.5" x 3.5" (no bigger or they dont fit in the baseball card holders)

You can get 10 trading cards from 1 sheet of cardstock:

Turn paper onto 8.5" size and cut it at:
3 1/2"  then  at 2 1/2" and 2 1/2" again

This leaves you with 3 strips of paper..
(one) 3 1/2" x 11
(two) 2 1/2" x 11

Now take the 3 1/2" x 11 strip,
turn it on the 11" side and cut every  2 1/2"

Then, take the 2 1/2" strips,
turn them on the 11: side and cut every 3 1/2"

You now have a total of 10 (ten) 2 1/2 x 3 1/2"  trading cards!