diff --git a/Number_Theory/A. Rational Resistance.cpp b/Number_Theory/A. Rational Resistance.cpp
new file mode 100644
index 0000000..9f923a8
--- /dev/null
+++ b/Number_Theory/A. Rational Resistance.cpp	
@@ -0,0 +1,21 @@
+#include <bits/stdc++.h>
+using namespace std;
+#define int long long
+signed  main(){
+    ios_base::sync_with_stdio(false);
+    cin.tie(0);
+    cout.tie(0);
+    int a, b;
+    cin>>a>>b;
+    int ans=0;
+    while(a&&b){
+        if(a>b){
+            ans+=a/b;
+            a%=b; 
+        }else{
+            ans+=b/a; 
+            b%=a;
+        }
+    }
+    cout<<ans<<"\n";
+}