diff --git a/units/en/unit7/self-play.mdx b/units/en/unit7/self-play.mdx
index 3fbd401..8dd44c7 100644
--- a/units/en/unit7/self-play.mdx
+++ b/units/en/unit7/self-play.mdx
@@ -113,7 +113,7 @@ Player B has a rating of 2300
 
 \\(ELO_A = 2600 + 16*(1-0.849) = 2602 \\)
 
-\\(ELO_B = 2300 + 16*(1-0.151) = 2298 \\)
+\\(ELO_B = 2300 + 16*(0-0.151) = 2298 \\)
 
 - If the organizers determined that K=16 and B wins, the new rating would be: