 Addition is the term \(\textsf{BS}(\textsf{BB})\), and multiplication is the term \(\textsf{B}\). The usual recursive definition of multiplication based on addition may suggest that addition should be a simpler operation than multiplication. However, in CL the numbers  themselves are functions, and so they have properties that allows  \(\textsf{B}\)—a simpler looking term—to be chosen for the function that is often perceived to be more complex than addition. (The addition operation could be defined using primitive recursion, which would produce a more complex term.) As a classical example, we may consider the term \(\textsf{BII}\), that is strongly equal to \(\textsf{I}\), that is,  \(1\times1=1\)—as expected. We do not pursue here this numerical representation further. We only note that the shape of these numbers is closely related to Church’s numerals in the \(\lambda\)-calculus, each of which is a binary function (whereas here, each number is a unary function).