Abhidhamma – Introduction

I think there is a typo in bullet 1 in this link: Abhidhamma – Introduction

When I add up the “basic units” it comes to 81. First reference to this number(highlighted) is typed as 82, should this be 81?

1. “Abhi” means “higher” or “deeper.” Thus Abhidhamma is a more in-depth, fundamental description of Buddha Dhamma.

The result is the same when compared with the material in the suttā, but Abhidhamma provides a “bottom-up” description of the existence, starting with 82 “most basic units” within the four ultimate entities of citta, cetasika, rūpa, and Nibbāna. That was a monumental task, and that is why it took almost 500 years to finalize it at the third Buddhist Council.
The 81 “basic units” that make up this world are one pure citta, 52 cetasika, and 28 types of rūpa. Depending on the combinations of cetasika that arise with citta, there will be 89 (or 121) types of contaminated citta (or viññāna) that can occur. That will become clear as we discuss further.