diff --git a/src/euler27/Cargo.toml b/src/euler27/Cargo.toml
new file mode 100644
index 0000000..2b3f298
--- /dev/null
+++ b/src/euler27/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+name = "euler27"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
diff --git a/src/euler27/src/main.rs b/src/euler27/src/main.rs
new file mode 100644
index 0000000..6cfd4b1
--- /dev/null
+++ b/src/euler27/src/main.rs
@@ -0,0 +1,47 @@
+use std::collections::HashMap;
+
+fn main() {
+    let q = Quadratic { a: 1, b: 41 };
+
+    let mut p = Primes::new();
+
+    for n in 0..=39 {
+        let result = q.calculate(n);
+        dbg!(p.is_prime(n));
+        println!("{}", result);
+    }
+}
+
+struct Quadratic {
+    a: isize,
+    b: isize,
+}
+
+impl Quadratic {
+    fn calculate(&self, n: isize) -> isize {
+        n.pow(2) + self.a * n + self.b
+    }
+}
+
+struct Primes(HashMap<isize, bool>);
+
+impl Primes {
+    fn new() -> Self {
+        let inner = HashMap::new();
+        Self(inner)
+    }
+
+    fn is_prime(&mut self, number: isize) -> bool {
+        let value = self.0.get(&number);
+        if let Some(result) = value {
+            return *result;
+        }
+        let is_prime = Self::test_primality(number);
+        self.0.insert(number, is_prime);
+        is_prime
+    }
+
+    fn test_primality(number: isize) -> bool {
+        let max = (number as f64).sqrt();
+    }
+}