便士 penny 是英镑中价值最小的货币单位。用一便士 a penny 就能买到的东西一般情况下不珍贵，而且价值较低。因此，表达 ten a penny “用一便士能买到十个”既说明该事物随处可见，价格很低，又可以形容一类人或一种行业“到处都有，多得遍地都是”。
Builders are ten a penny, but it can be hard to find one you trust.
Coffee shops are ten a penny on many high streets today.
TV talent shows are ten a penny these days. Every channel seems to have singing, dancing or cooking competitions on every day.
相反，如果某人为了一个事物花费了 a pretty penny “相当多的便士”，那么说明它非常贵重。
Wow, look at that car. That must have cost a pretty penny!
Rare toys in their original boxes, unopened, can be worth a pretty penny.