Update Twitter back-of-the-envelope calculations (donnemartin#414)

kof-f · web-flow · commit 914736a29f2b · 2020-07-04T10:55:42.000-04:00
diff --git a/solutions/system_design/twitter/README.md b/solutions/system_design/twitter/README.md
@@ -80,6 +80,7 @@ Search
 * 60 thousand tweets delivered on fanout per second
     * 150 billion tweets delivered on fanout per month * (400 requests per second / 1 billion requests per month)
 * 4,000 search requests per second
+    * 10 billion searches per month * (400 requests per second / 1 billion requests per month)
 
 Handy conversion guide:
 
