Add GCD, LCM and main scripts

script_GCD.sh

@@ -0,0 +1,15 @@
+#!/bin/bash
+# script_GCD.sh
+
+gcd() {
+    a=$1
+    b=$2
+    while [ $b -ne 0 ]; do
+        temp=$b
+        b=$((a % b))
+        a=$temp
+    done
+    echo $a
+}
+
+gcd $1 $2