A document calculates the number of cheerios that would fit in a classroom and the number needed to reach 1 billion cheerios. It finds that a small box can hold 1,588 cheerios and a typical classroom measures 313 by 336 by 113 inches and can hold over 197 million cheerios. To reach 1 billion cheerios would require around 30 full classrooms. The document aims to illustrate just how large the number 1 billion is.