Verified Answer :

I assume, that this pen is rectangular. 

Look, that  48 = 24 2 = 12 2 2 = 3 2 2 2 2
And know choose these numbers and multiply! 

First dimension:  3
2 x 222 = 6 x 8
Second:   3 x 2222 = 3 x 16
Third: 3
22 x 22 = 12 x 4
Fourth: 3222 x 2 = 24 x 2
Fifth: 48 x 1
Sixth dimension cannot be integer. So you can for example save this  as
48 = 3
16 = 1.5 2 16 = 1.5 * 32

Sixth dimension:  1.5  x  32

NOTE: each dimensions are in feet!