diff --git a/algorithms/gcd.cpp b/algorithms/gcd.cpp
new file mode 100644
index 00000000..9757039f
--- /dev/null
+++ b/algorithms/gcd.cpp
@@ -0,0 +1,28 @@
+#include<bits/stdc++.h>
+using namespace std;
+char c[250];
+int rem(int a)
+{
+    int t=0,b=0;
+    while(c[t]!='\0')
+    {
+        b=(b*10)+c[t]-48;
+        b=b%a;
+        t++;
+    }
+return b;
+}
+int main()
+{
+   int t,a;
+   scanf("%d",&t);
+   while(t--)
+   {
+       scanf("%d",&a);
+       scanf("%s",&c);
+       if(!a)
+            printf("%s\n",c);
+       else
+       printf("%d\n",__gcd(a,rem(a)));
+   }
+}