Clarify behavior of integer division. Fixes #2248.

listings/ch03-common-programming-concepts/no-listing-07-numeric-operations/src/main.rs

@@ -10,6 +10,7 @@ fn main() {
 
     // division
     let quotient = 56.7 / 32.2;
+    let floored = 2 / 3; // Results in 0
 
     // remainder
     let remainder = 43 % 5;

src/ch03-02-data-types.md

@@ -147,7 +147,8 @@ Floating-point numbers are represented according to the IEEE-754 standard. The
 
 Rust supports the basic mathematical operations you’d expect for all of the
 number types: addition, subtraction, multiplication, division, and remainder.
-The following code shows how you’d use each one in a `let` statement:
+Integer division rounds down to the nearest integer. The following code shows
+how you’d use each numeric operation in a `let` statement:
 
 <span class="filename">Filename: src/main.rs</span>