diff --git a/166_fraction_to_recurring_decimal/Cargo.lock b/166_fraction_to_recurring_decimal/Cargo.lock
new file mode 100644
index 0000000..378a316
--- /dev/null
+++ b/166_fraction_to_recurring_decimal/Cargo.lock
@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "fraction_to_recurring_decimal"
+version = "0.1.0"
diff --git a/166_fraction_to_recurring_decimal/Cargo.toml b/166_fraction_to_recurring_decimal/Cargo.toml
new file mode 100644
index 0000000..273ee32
--- /dev/null
+++ b/166_fraction_to_recurring_decimal/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+name = "fraction_to_recurring_decimal"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
diff --git a/166_fraction_to_recurring_decimal/src/lib.rs b/166_fraction_to_recurring_decimal/src/lib.rs
new file mode 100644
index 0000000..3bb05b0
--- /dev/null
+++ b/166_fraction_to_recurring_decimal/src/lib.rs
@@ -0,0 +1,61 @@
+pub struct Solution;
+
+impl Solution {
+    pub fn fraction_to_decimal(numerator: i32, denominator: i32) -> String {
+        if numerator == 0 {
+            return "0".to_string();
+        }
+
+        let mut result = String::new();
+
+        if numerator.is_negative() != denominator.is_negative() {
+            result.push('-');
+        }
+        let mut numerator = numerator.unsigned_abs() as u64;
+        let mut denominator = denominator.unsigned_abs() as u64;
+
+        let gcd = Solution::gcd(numerator, denominator);
+        numerator /= gcd;
+        denominator /= gcd;
+
+        result.push_str(&(numerator / denominator).to_string());
+        if numerator % denominator == 0 {
+            return result;
+        }
+
+        result.push('.');
+
+        let mut remains = std::collections::HashMap::<u64, usize>::new();
+        loop {
+            remains.insert(numerator % denominator, result.len());
+            numerator %= denominator;
+            numerator *= 10;
+            result.push(((numerator / denominator) as u8 + '0' as u8) as char);
+
+            if result.len() >= 10000 {
+                break;
+            }
+
+            let remain = numerator % denominator;
+            if remain == 0 {
+                break;
+            } else if let Some(index) = remains.get(&remain) {
+                result.insert(*index, '(');
+                result.push(')');
+                break;
+            }
+        }
+
+        result
+    }
+
+    fn gcd(a: u64, b: u64) -> u64 {
+        if a == 0 {
+            b
+        } else if a <= b {
+            Solution::gcd(b % a, a)
+        } else {
+            Solution::gcd(b, a)
+        }
+    }
+}