In addition to indicating order or ranking, 100th can also be used to indicate percentage. In mathematics, 100th usually means that the denominator of a fraction is 100. For example, "one third" can be expressed as 333% or 0.33, which can be simplified as 1/3, that is, "one third".
In daily life, we may encounter some problems related to ordering goods, such as limited goods that are common in online shopping. At this time, merchants often indicate "only 100 pieces left" or "only 100 customers left". At this time, 100th means quantity limit, that is, only 100 items or 100 customers can enjoy special discounts.