Locke notoriously included number amongst the primary qualities of bodies and was roundly criticized for doing so by Berkeley. Frege echoed some of Berkeley's criticisms in attacking the idea that ‘Number is a property of external things’, while defending his own view that number is a property of concepts. In the present paper, Locke's view is defended against the objections of Berkeley and Frege, and Frege's alternative view of number is criticized. More precisely, it is argued that numbers are assignable to pluralities of individuals. However, it is also argued that Locke went too far in asserting that ‘Number applies itself to ... everything that either doth exist, or can be imagined’.