Frederick’s (2005) Cognitive Reflection Test (CRT) is a 3-item task shown to predict susceptibility to decision-making biases better than intelligence measures. It is described as measuring ‘cognitive reflection’ - a metacognitive trait capturing the degree to which people prefer to reflect on answers rather than giving intuitive responses. Herein, we ask how much of the CRT’s success can be explained by assuming it is a test of numerical (rather than general) intelligence. Our results show CRT is closely related to numerical ability and that its predictive power is limited to biases with a numerical basis. Although it may also capture some aspect of a rational cognition decision style, it is unrelated to a metacognitive, error-checking and inhibition measure. We conclude that the predictive power of the CRT can, largely, be explained via numerical ability without the need to posit a separate ‘cognitive reflection’ trait.