Train students to quickly identify the number of items in a small set without counting with this set of 3 red and 3 blue ten-sided dice. 20mm subitizing dice depicts number patterns zero to nine. Perceptual subitizing is quickly recognizing the cardinality of small groups without counting. Perceptual subitizing progresses into conceptual subitizing, where quantities of larger groups are determined by quickly subitizing and combining smaller groups (i.e. 3 groups of five items for the number 15, or 2 groups of 10 for the number 20). Conceptual subitizing progresses into supporting more advanced methods for addition, subtraction, multiplication, and division.