Twenty-One helps some new friends find out how many rectangles they can make. Learn about the numbers 23 and 24.
The episode starts with 21-24 working out at Ten's Place. After their workout, Twenty-Four wonders if they'll ever figure themselves out. Twenty-One decides to help them out.
They go to the Rectangle Retreat where Twelve is doing yoga. Twenty-One states that figuring out what types of rectangles a number can make can make them easier to figure themselves out. After asking if Twelve if they can help the two compound Numberblocks figure themselves out, Twelve and Eighteen soon agree to help them out.
The two compound Numberblocks start figuring out what rectangles they can make, starting with their prime positions (one block wide by their number tall, and one block tall by their number wide). Twenty-Four manages to make eight rectangles (1x24, 2x12, 3x8, 4x6, 6x4, 8x3, 12x2, and 24x1), while Twenty-Three only manages to make two; 1x23 and 23x1, their prime positions. Twenty-Four proceeds to figure herself out, becoming a super-duper rectangle. Meanwhile, Twenty-Three figures himself out, affirming that he is a prime number.