How many demi semi quavers in a crochet?

A crochet (quarter note) is equivalent to four demi-semiquavers (thirty-second notes). This is because a demi-semiquaver is half the duration of a semi-quaver (eighth note), and a semi-quaver is half the duration of a crochet. Therefore, it takes four demi-semiquavers to match the length of one crochet.