'Thirty' in the Bible

If the ox gores a male or a female servant, the owner shall give to the servant’s master thirty shekels of silver [the purchase price for a slave], and the ox shall be stoned.

Each curtain shall be thirty cubits long and four cubits wide. The eleven curtains shall all measure the same.

Each curtain was thirty cubits long and four cubits wide; the eleven curtains were of equal size.