diff --git a/DIRECTORY.md b/DIRECTORY.md
index 805c9e73ab1b..6bf7096df968 100644
--- a/DIRECTORY.md
+++ b/DIRECTORY.md
@@ -237,6 +237,7 @@
             * [EulerMethod](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/maths/EulerMethod.java)
             * [Factorial](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/maths/Factorial.java)
             * [FactorialRecursion](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/maths/FactorialRecursion.java)
+            * [FastInverseSqrt](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/maths/FastInverseSqrt.java)
             * [FFT](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/maths/FFT.java)
             * [FFTBluestein](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/maths/FFTBluestein.java)
             * [FibonacciJavaStreams](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/maths/FibonacciJavaStreams.java)
@@ -493,6 +494,7 @@
             * [DigitalRootTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/DigitalRootTest.java)
             * [DistanceFormulaTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/DistanceFormulaTest.java)
             * [FactorialTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/FactorialTest.java)
+            * [FastInverseSqrtTests](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/FastInverseSqrtTests.java)
             * [FFTTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/FFTTest.java)
             * [FindMaxTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/FindMaxTest.java)
             * [FindMinTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/FindMinTest.java)