ثَلَاثَةَ قُرُوءٍ
Three qurūʾ. (Qurʾān 2:228)
The term qurʾ is interpreted in legal discussions as either menstruation or a period of purity. The choice changes how a divorced woman's waiting period is counted.
The question is not the number of women or instances of a single known meaning. The problem is which of two established meanings the verse intends.
The Hanafi position selects menstruation, while the Shafiʿi position selects purity. This is a classic application of the principle governing ambiguous homonymous wording.