Exodus 26:12

And the part that remains of the curtains of the tent, the half curtain that remains, shall hang over the back of the tabernacle.

Treasury of Scripture Knowledge

And the remnant that remaineth of the curtains of the tent, the half curtain that remaineth, shall hang over the backside of the tabernacle.

You shall couple five curtains by themselves, and six curtains by themselves, and the sixth curtain you shall double over at the front of the tent.