Add LCM script and update main

script_LCM.sh

@@ -0,0 +1,18 @@
+#!/bin/bash 
+
+if [ $# -ne 2 ]; then
+    echo "error, pls write 2 arguments"
+    exit 1
+fi
+
+a=$1
+b=$2
+
+GCD=$(bash ./script_GCD.sh $a $b | head -n1)
+ 
+if ! [[ "$GCD" =~ ^[0-9]+$ ]]; then
+    echo "Error"
+    exit 1
+fi
+
+echo $(( ($a * $b) / $GCD ))