diff --git a/docs/ApplicationArchitecture.md b/docs/ApplicationArchitecture.md
index 0d7c2ff3..c6d59b34 100644
--- a/docs/ApplicationArchitecture.md
+++ b/docs/ApplicationArchitecture.md
@@ -153,7 +153,7 @@ The CalcEngine contains the logic for interpreting and performing operations acc
 
 ### RatPack
 
-The RatPack (short for Rational Pack) is the core of the Calculator model and contains the logic for performing its mathematical operations. The interface to this layer is defined in [ratpak.h][ratpak.h].
+The RatPack (short for Rational Pack) is the core of the Calculator model and contains the logic for performing its mathematical operations (uses arbitrary-precision arithmetic instead of regular floating point arithmetic). The interface to this layer is defined in [ratpak.h][ratpak.h].
 
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