diff --git a/src/main/java/com/thealgorithms/ciphers/AES.java b/src/main/java/com/thealgorithms/ciphers/AES.java
index 65c6ce79..c5cb286c 100644
--- a/src/main/java/com/thealgorithms/ciphers/AES.java
+++ b/src/main/java/com/thealgorithms/ciphers/AES.java
@@ -2438,16 +2438,16 @@ public class AES {
     public static BigInteger[] keyExpansion(BigInteger initialKey) {
         BigInteger[] roundKeys = {
             initialKey,
-            new BigInteger("0"),
-            new BigInteger("0"),
-            new BigInteger("0"),
-            new BigInteger("0"),
-            new BigInteger("0"),
-            new BigInteger("0"),
-            new BigInteger("0"),
-            new BigInteger("0"),
-            new BigInteger("0"),
-            new BigInteger("0"),
+                BigInteger.ZERO,
+                BigInteger.ZERO,
+                BigInteger.ZERO,
+                BigInteger.ZERO,
+                BigInteger.ZERO,
+                BigInteger.ZERO,
+                BigInteger.ZERO,
+                BigInteger.ZERO,
+                BigInteger.ZERO,
+                BigInteger.ZERO,
         };
 
         // initialize rcon iteration
diff --git a/src/main/java/com/thealgorithms/ciphers/RSA.java b/src/main/java/com/thealgorithms/ciphers/RSA.java
index fcce53cb..08f4e198 100644
--- a/src/main/java/com/thealgorithms/ciphers/RSA.java
+++ b/src/main/java/com/thealgorithms/ciphers/RSA.java
@@ -63,7 +63,7 @@ public class RSA {
         publicKey = BigInteger.valueOf(3L);
 
         while (m.gcd(publicKey).intValue() > 1) {
-            publicKey = publicKey.add(BigInteger.valueOf(2L));
+            publicKey = publicKey.add(BigInteger.TWO);
         }
 
         privateKey = publicKey.modInverse(m);
diff --git a/src/main/java/com/thealgorithms/maths/KaprekarNumbers.java b/src/main/java/com/thealgorithms/maths/KaprekarNumbers.java
index 2d15dc4f..a932dc77 100644
--- a/src/main/java/com/thealgorithms/maths/KaprekarNumbers.java
+++ b/src/main/java/com/thealgorithms/maths/KaprekarNumbers.java
@@ -10,7 +10,7 @@ public class KaprekarNumbers {
 	digits and sum of these parts is equal to the original number. */
 
     // Provides a list of kaprekarNumber in a range
-    public static ArrayList<Long> kaprekarNumberInRange(long start, long end)
+    public static List<Long> kaprekarNumberInRange(long start, long end)
         throws Exception {
         long n = end - start;
         if (n < 0) throw new Exception("Invalid range");
@@ -26,12 +26,12 @@ public class KaprekarNumbers {
     // Checks whether a given number is Kaprekar Number or not
     public static boolean isKaprekarNumber(long num) {
         String number = Long.toString(num);
-        BigInteger originalNumber = new BigInteger(number);
+        BigInteger originalNumber = BigInteger.valueOf(num);
         BigInteger numberSquared = originalNumber.multiply(originalNumber);
         if (number.length() == numberSquared.toString().length()) {
             return number.equals(numberSquared.toString());
         } else {
-            BigInteger leftDigits1 = new BigInteger("0");
+            BigInteger leftDigits1 = BigInteger.ZERO;
             BigInteger leftDigits2;
             if (numberSquared.toString().contains("0")) {
                 leftDigits1 =
diff --git a/src/test/java/com/thealgorithms/maths/KaprekarNumbersTest.java b/src/test/java/com/thealgorithms/maths/KaprekarNumbersTest.java
index 98c7baa2..326c1a9a 100644
--- a/src/test/java/com/thealgorithms/maths/KaprekarNumbersTest.java
+++ b/src/test/java/com/thealgorithms/maths/KaprekarNumbersTest.java
@@ -2,7 +2,8 @@ package com.thealgorithms.maths;
 
 import static org.junit.jupiter.api.Assertions.*;
 
-import java.util.ArrayList;
+import java.util.List;
+
 import org.junit.jupiter.api.Test;
 
 public class KaprekarNumbersTest {
@@ -50,7 +51,7 @@ public class KaprekarNumbersTest {
     @Test
     void testForRangeOfNumber() {
         try {
-            ArrayList<Long> rangedNumbers = KaprekarNumbers.kaprekarNumberInRange(
+            List<Long> rangedNumbers = KaprekarNumbers.kaprekarNumberInRange(
                 1,
                 100000
             );