After the blindfolds were removed, each woman in turn was asked to name the number on her forehead without seeing it. The question was repeated until only one woman failed to name the number on her forehead.
When it was logically possible to name the number on her forehead, each woman did so; when it was not logically possible to name the number on her forehead, she would said "I don´t know my number", and waited until the question was repeated to her next time around.
Each woman had a 2 on her forehead. Which woman failed to name her number?