In 211 BC during the 2nd Punic war, Rome went on a silver monetary standard based on the denarius. It was pegged at 10 bronze asses to the denarius. This value was represented on the obverse of the coin with an X, the Roman numeral for 10. Around 141 BC the denarius was devalued to 16 asses to the denarius. This value was represented on the coin with XVI, the Roman numeral for 16. It could be read counterclockwise, or it could be read clockwise. This Roman numeral valuation didn't last too long, and about 136 BC it was replaced with a monogram representing the numeral 16. Then around 110 BC the designation of the value of a denarius in asses was no longer used on the coin. I am not sure why this came about, but it may have been because of the continual debasement of the as. The next coin is a fairly rare error on the part of the celator when he made the dies for the denarius. You will notice that the V is inverted and the value can not be read correctly either clockwise or counterclockwise. One of these coins just sold for $500 and another has a high bid at this time of $600. This quite a rarity that I would like to own, but it is out of my reach right now.