The Numberblocks MathLink Cubes 21–30 set allows children to build numbers Twenty-one through Thirty in multiple configurations, just as seen in the episodes. It includes 10 double-sided activity cards with episode-linked exercises, enabling kids to watch and learn simultaneously. Character cards provide visual references for each number’s position on a number line, reinforcing place value concepts without relying on text. This set expands on the MathLink Cubes Numberblocks 1–10 and 11–20 Activity Sets, sold separately. The package contains 235 MathLink Cubes, 20 dual connector cubes, 38 face plates, 10 Numberlings, 3 accessories, a sticker sheet, 10 activity cards, 10 character cards, and a multilingual Activity Guide. Produced by Learning Resources, these are officially licensed Numberblocks educational toys.