The seven positions are easier to remember in three groups:
ExamplesCountGroup
يَفْعُلَانِ, تَفْعُلَانِ4 positionsall dual forms
يَفْعُلُونَ, تَفْعُلُونَ2 positionsmasculine plural
تَفْعُلِينَ1 positionsingular feminine Haadhir
Memory formula: 4 dual + 2 masculine plural + 1 singular feminine Haadhir = 7.