diff --git a/src/euler45/Cargo.toml b/src/euler45/Cargo.toml
new file mode 100644
index 0000000..74b0ca4
--- /dev/null
+++ b/src/euler45/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+name = "euler45"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
diff --git a/src/euler45/src/main.rs b/src/euler45/src/main.rs
new file mode 100644
index 0000000..b8c6886
--- /dev/null
+++ b/src/euler45/src/main.rs
@@ -0,0 +1,26 @@
+use std::collections::HashSet;
+
+fn main() {
+    let triangle_numbers: Vec<_> = (286..100_000).map(triangle).collect();
+    let pentagonal_numbers: HashSet<_> = (2..100_000).map(pentagonal).collect();
+    let hexagonal_numbers: HashSet<_> = (2..100_000).map(hexagonal).collect();
+
+    for t in triangle_numbers {
+        if pentagonal_numbers.contains(&t) && hexagonal_numbers.contains(&t) {
+            println!("{t}");
+            break;
+        }
+    }
+}
+
+fn triangle(n: usize) -> usize {
+    n * (n + 1) / 2
+}
+
+fn pentagonal(n: usize) -> usize {
+    n * (3 * n - 1) / 2
+}
+
+fn hexagonal(n: usize) -> usize {
+    n * (2 * n - 1)
+}