The development of numerical ordering of number symbols, unlike numerical ordering of other stimuli, such as sets of everyday items, has recently gained growing research interest. Here, we report a nine-year follow-up study with 36 three-year-old children. We investigated how children’s focusing on numerical order develops alongside number sequence production and cardinality recognition skills. Results showed large individual and developmental differences in children’s focusing on numerical order from the ages of 3 to 6 years. Preschool focusing on numerical order and spontaneous focusing on numerosity predicted curriculum-based math achievement at 12 years of age.