How is the 'iddah (waiting period) for divorce calculated for a woman who was divorced during a period of purity, was not touched, has her menstrual cycle every four months, and her period came two months and ten days after the divorce?

The divorced woman who menstruates has an 'iddah (waiting period) of three menstrual cycles, based on the Almighty's saying: "Divorced women shall wait concerning themselves for three menstrual periods." The spaced-out nature of her menstrual periods does not affect this as long as she has not reached menopause. The 'iddah begins from the date of the divorce, even if the husband had not had intercourse with her for a period before the divorce. The divorce takes effect even if it violates the Sunnah by occurring during a period of purity in which he had touched her.