diff --git a/src/main/java/me/hatter/math/pi/PowPiFrac6.java b/src/main/java/me/hatter/math/pi/PowPiFrac6.java
index 0ee4742..778aa25 100644
--- a/src/main/java/me/hatter/math/pi/PowPiFrac6.java
+++ b/src/main/java/me/hatter/math/pi/PowPiFrac6.java
@@ -12,6 +12,7 @@ public class PowPiFrac6 {
         System.out.println(pi());
     }
 
+    // \sqrt{6\cdot \sum_{i=1}^{\infty} \frac{1}{i^2}}
     public static BigDecimal pi() {
         BigDecimal t = BigDecimal.ZERO;
         for (long i = 1; i < 10000000; i++) {