diff --git a/Utils/LinqExtensions.cs b/Utils/Extensions/LinqExtensions.cs
similarity index 95%
rename from Utils/LinqExtensions.cs
rename to Utils/Extensions/LinqExtensions.cs
index f417bf2..39c10ef 100644
--- a/Utils/LinqExtensions.cs
+++ b/Utils/Extensions/LinqExtensions.cs
@@ -1,4 +1,4 @@
-namespace AdventOfCode.Utils;
+namespace AdventOfCode.Utils.Extensions;
 
 public static class LinqExtensions
 {
@@ -9,9 +9,11 @@ public static class LinqExtensions
     /// <param name="startIndex">The first index of the slice</param>
     /// <param name="endIndex">The index after the last index of the slice</param>
     /// <returns></returns>
-    public static List<T> Sublist<T>(this List<T> list, int startIndex, int endIndex)
+    public static List<T> Sublist<T>(this List<T> list, int startIndex, int endIndex = default)
     {
         List<T> result = new List<T>();
+        if (endIndex == default)
+            endIndex = list.Count;
         for (int i = startIndex; i < endIndex; i++)
             result.Add(list[i]);
         return result;
diff --git a/Utils/Extensions/MathExtensions.cs b/Utils/Extensions/MathExtensions.cs
new file mode 100644
index 0000000..384587d
--- /dev/null
+++ b/Utils/Extensions/MathExtensions.cs
@@ -0,0 +1,58 @@
+namespace AdventOfCode.Utils.Extensions;
+
+public static class MathExtensions
+{
+    public static int Signal(this int x)
+    {
+        return x switch
+        {
+            < 0 => -1,
+            > 0 => 1,
+            _ => 0
+        };
+    }
+
+    public static bool IsDigit(this string s)
+    {
+        try
+        {
+            Convert.ToInt32(s);
+        }
+        catch (FormatException ignored)
+        {
+            return false;
+        }
+
+        return true;
+    }
+
+    public static ulong ProductOfMax(this List<ulong> list, int maxCount)
+    {
+        List<ulong> maxList = new List<ulong>(maxCount);
+
+        foreach (ulong number in list)
+        {
+            if (maxList.Count < maxList.Capacity)
+                maxList.Add(number);
+            else
+            if (number > maxList.Min())
+            {
+                maxList.RemoveAt(0);
+                maxList.Add(number);
+            }
+            maxList.Sort();
+        }
+
+        ulong product = 1;
+        maxList.ForEach(n => product*=n);
+        return product;
+    }
+
+    public static int LeastCommonMultiplier(this List<int> list)
+    {
+        int lcm = 1;
+        foreach (int i in list)
+            lcm *= i / MathTools.GreatCommonDivider(lcm, i);
+        return lcm;
+    }
+}
\ No newline at end of file
diff --git a/Utils/MathExtensions.cs b/Utils/MathExtensions.cs
deleted file mode 100644
index 7785629..0000000
--- a/Utils/MathExtensions.cs
+++ /dev/null
@@ -1,14 +0,0 @@
-namespace AdventOfCode.Utils;
-
-public static class MathExtensions
-{
-    public static int Signal(this int x)
-    {
-        return x switch
-        {
-            < 0 => -1,
-            > 0 => 1,
-            _ => 0
-        };
-    }
-}
\ No newline at end of file
diff --git a/Utils/MathTools.cs b/Utils/MathTools.cs
new file mode 100644
index 0000000..b37b4fd
--- /dev/null
+++ b/Utils/MathTools.cs
@@ -0,0 +1,11 @@
+namespace AdventOfCode.Utils;
+
+public static class MathTools
+{
+    public static int GreatCommonDivider(int x, int y)
+    {
+        if (x % y == 0)
+            return y;
+        return GreatCommonDivider(y, x % y);
+    }
+}
\ No newline at end of file
diff --git a/Year2022/Day5.cs b/Year2022/Day5.cs
index 080550f..1842252 100644
--- a/Year2022/Day5.cs
+++ b/Year2022/Day5.cs
@@ -1,4 +1,4 @@
-using AdventOfCode.Utils;
+using AdventOfCode.Utils.Extensions;
 
 namespace AdventOfCode.Year2022;
 
diff --git a/Year2022/Day8.cs b/Year2022/Day8.cs
index 34d467b..e0a3cce 100644
--- a/Year2022/Day8.cs
+++ b/Year2022/Day8.cs
@@ -1,4 +1,4 @@
-using AdventOfCode.Utils;
+using AdventOfCode.Utils.Extensions;
 
 namespace AdventOfCode.Year2022;
 
diff --git a/Year2022/Day9.cs b/Year2022/Day9.cs
index dcf8849..33d6642 100644
--- a/Year2022/Day9.cs
+++ b/Year2022/Day9.cs
@@ -1,4 +1,4 @@
-using AdventOfCode.Utils;
+using AdventOfCode.Utils.Extensions;
 
 namespace AdventOfCode.Year2022;