diff --git a/src/es02_rational.rs b/src/es02_rational.rs
new file mode 100644
index 0000000..7cdcdec
--- /dev/null
+++ b/src/es02_rational.rs
@@ -0,0 +1,58 @@
+#![allow(dead_code)]
+
+/** Es.2
+ * Si definisca un modulo razionali che contiene una implementazione dei numeri razionali,
+ * cioe’ una struttura Razionali con i due campi interi num e denum (per numeratore e denominatore)
+ * i metodi di somma, prodotto, e riduzione ai minimi termini (dividere num e denum per il massimo comun divisore)
+ * le funzioni new che ritorna un Razionale (con 2 parametri) e int_to_raz che prende un intero
+ * e ritorna il numero razionale che ha quell’intero come numeratore e 1 come denominatore.
+ */
+
+#[derive(Debug, PartialEq, Clone)]
+pub struct Rational {
+    num: i32,
+    den: i32,
+}
+
+impl Rational {
+    pub fn new(num: i32, den: i32) -> Self {
+        assert!(den != 0, "Cannot divide by zero!");
+
+        let mut numero = Rational { num, den };
+        numero.reduce();
+        numero
+    }
+    pub fn from(int: i32) -> Self {
+        Rational { num: int, den: 1 }
+    }
+
+    pub fn multiplication(&mut self, other: &Rational) -> &mut Self {
+        self.num *= other.num;
+        self.den *= other.den;
+        self.reduce()
+    }
+    pub fn addition(&mut self, other: &Rational) -> &mut Self {
+        self.num = (self.num * other.den) + (other.num * self.den);
+        self.den *= other.den;
+        self.reduce()
+    }
+    fn reduce(&mut self) -> &mut Self {
+        if self.den < 0 {
+            self.num *= -1;
+            self.den *= -1;
+        }
+
+        let mcd = Self::mcd(self.num, self.den);
+        self.num /= mcd;
+        self.den /= mcd;
+        self
+    }
+    fn mcd(a: i32, b: i32) -> i32 {
+        // mcd Euclideo https://en.wikipedia.org/wiki/Euclidean_algorithm#Implementations
+        if b == 0 {
+            a
+        } else {
+            Self::mcd(b, a % b)
+        }
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 5015d3a..1cdcdf3 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1 +1,2 @@
 pub mod es01_anagram;
+pub mod es02_rational;
diff --git a/tests/es02_rational.rs b/tests/es02_rational.rs
new file mode 100644
index 0000000..b28effb
--- /dev/null
+++ b/tests/es02_rational.rs
@@ -0,0 +1,46 @@
+use esercizi::es02_rational::Rational;
+
+#[test]
+fn test_razionali() {
+    assert_eq!(
+        Rational::new(2, 3).multiplication(&Rational::new(3, 2)),
+        &Rational::new(1, 1)
+    );
+    assert_eq!(
+        Rational::new(4, 3).multiplication(&Rational::new(5, 7)),
+        &Rational::new(20, 21)
+    );
+    assert_eq!(
+        Rational::new(-3, 2).multiplication(&Rational::new(7, 4)),
+        &Rational::new(-21, 8)
+    );
+    assert_eq!(
+        Rational::new(-3, 2).multiplication(&Rational::new(14, 14)),
+        &Rational::new(-3, 2)
+    );
+    assert_eq!(
+        Rational::new(2, 3).addition(&Rational::new(3, 2)),
+        &Rational::new(13, 6)
+    );
+    assert_eq!(
+        Rational::new(5, 3).addition(&Rational::new(5, 2)),
+        &Rational::new(25, 6)
+    );
+    assert_eq!(
+        Rational::new(-3, 16).addition(&Rational::new(5, -4)),
+        &Rational::new(-23, 16)
+    );
+    assert_eq!(
+        Rational::from(100).addition(&Rational::from(47)),
+        &Rational::from(147)
+    );
+    assert_eq!(
+        Rational::new(23, 12)
+            .addition(&Rational::new(24, 15))
+            .addition(&Rational::new(23, 24))
+            .addition(&Rational::new(-437, 120)),
+        &Rational::new(5, 6)
+    );
+    assert_eq!(Rational::new(-2, 4), Rational::new(-1, 2));
+    assert_eq!(Rational::new(4, -2), Rational::new(-2, 1))
+}