diff --git a/book/book.tex b/book/book.tex
index 98052b39..08cf2f49 100644
--- a/book/book.tex
+++ b/book/book.tex
@@ -786,7 +786,7 @@ \section{The axes of scientific models}
 \item[One, two \myrightarrow~many] Classical models are often limited to
   small numbers of components.  For example, in celestial mechanics the
   two-body problem can be solved analytically; the three-body problem
-  cannot.  Complexity science often works with large numbers of components and larger number of interactions.
+  cannot.  Complexity science often works with large numbers of components and larger numbers of interactions.
 
 \index{one, two, many}