diff --git a/Cargo.lock b/Cargo.lock
index d2e46eb..f0b4a5f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -256,7 +256,7 @@ dependencies = [
 name = "cainome-cairo-serde"
 version = "0.1.0"
 dependencies = [
- "num-bigint",
+ "num",
  "serde",
  "serde_with",
  "starknet",
@@ -1114,6 +1114,20 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "num"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "35bd024e8b2ff75562e5f34e7f4905839deb4b22955ef5e73d2fea1b9813cb23"
+dependencies = [
+ "num-bigint",
+ "num-complex",
+ "num-integer",
+ "num-iter",
+ "num-rational",
+ "num-traits",
+]
+
 [[package]]
 name = "num-bigint"
 version = "0.4.6"
@@ -1124,6 +1138,15 @@ dependencies = [
  "num-traits",
 ]
 
+[[package]]
+name = "num-complex"
+version = "0.4.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "73f88a1307638156682bada9d7604135552957b7818057dcef22705b4d509495"
+dependencies = [
+ "num-traits",
+]
+
 [[package]]
 name = "num-conv"
 version = "0.1.0"
@@ -1139,6 +1162,28 @@ dependencies = [
  "num-traits",
 ]
 
+[[package]]
+name = "num-iter"
+version = "0.1.45"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1429034a0490724d0075ebb2bc9e875d6503c3cf69e235a8941aa757d83ef5bf"
+dependencies = [
+ "autocfg",
+ "num-integer",
+ "num-traits",
+]
+
+[[package]]
+name = "num-rational"
+version = "0.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f83d14da390562dca69fc84082e73e548e1ad308d24accdedd2720017cb37824"
+dependencies = [
+ "num-bigint",
+ "num-integer",
+ "num-traits",
+]
+
 [[package]]
 name = "num-traits"
 version = "0.2.19"
diff --git a/Cargo.toml b/Cargo.toml
index 559f381..da62d8f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -21,7 +21,7 @@ cainome-rs = { path = "crates/rs" }
 
 anyhow = "1.0"
 async-trait = "0.1"
-num-bigint = "0.4.6"
+num = "0.4.3"
 camino = { version = "1.1", features = ["serde1"] }
 convert_case = "0.6"
 serde = { version = "1.0", default-features = false, features = ["alloc"] }
diff --git a/crates/cairo-serde/Cargo.toml b/crates/cairo-serde/Cargo.toml
index 7995d95..672e11c 100644
--- a/crates/cairo-serde/Cargo.toml
+++ b/crates/cairo-serde/Cargo.toml
@@ -10,4 +10,4 @@ starknet.workspace = true
 thiserror.workspace = true
 serde.workspace = true
 serde_with = { version = "3.11.0", default-features = false }
-num-bigint.workspace = true
+num.workspace = true
diff --git a/crates/cairo-serde/src/types/u256.rs b/crates/cairo-serde/src/types/u256.rs
index d518e95..bf48225 100644
--- a/crates/cairo-serde/src/types/u256.rs
+++ b/crates/cairo-serde/src/types/u256.rs
@@ -1,20 +1,62 @@
 use crate::CairoSerde;
-use num_bigint::{BigInt, BigUint, ParseBigIntError};
+use num::{bigint::ParseBigIntError, BigUint, Num};
 use serde_with::{DeserializeAs, DisplayFromStr, SerializeAs};
-use starknet::core::types::Felt;
+use starknet::core::types::{Felt, U256 as StarknetU256};
 use std::{
     cmp::Ordering,
     fmt::Display,
-    ops::{Add, BitOr, Sub},
+    ops::{Add, BitOr, Mul, Sub},
     str::FromStr,
 };
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
 pub struct U256 {
     pub low: u128,
     pub high: u128,
 }
 
+impl U256 {
+    pub const ZERO: U256 = Self::from_u128(0);
+    pub const ONE: U256 = Self::from_u128(1);
+    pub const TWO: U256 = Self::from_u128(2);
+
+    const fn from_u128(value: u128) -> Self {
+        U256 {
+            low: value,
+            high: 0,
+        }
+    }
+}
+
+macro_rules! impl_from_for_u256 {
+    ($($t:ty),*) => {
+        $(
+            impl From<$t> for U256 {
+                fn from(value: $t) -> Self {
+                    Self::from_u128(value as u128)
+                }
+            }
+        )*
+    };
+}
+
+impl_from_for_u256!(u8, u16, u32, u64, u128, usize);
+
+impl From<StarknetU256> for U256 {
+    fn from(value: StarknetU256) -> Self {
+        Self {
+            low: value.low(),
+            high: value.high(),
+        }
+    }
+}
+
+impl From<U256> for StarknetU256 {
+    fn from(value: U256) -> Self {
+        StarknetU256::from_words(value.low, value.high)
+    }
+}
+
 impl PartialOrd for U256 {
     fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
         Some(match self.high.cmp(&other.high) {
@@ -59,6 +101,14 @@ impl Sub for U256 {
     }
 }
 
+impl Mul for U256 {
+    type Output = Self;
+
+    fn mul(self, rhs: Self) -> Self::Output {
+        (StarknetU256::from(self) * StarknetU256::from(rhs)).into()
+    }
+}
+
 impl BitOr for U256 {
     type Output = Self;
 
@@ -76,18 +126,22 @@ impl Display for U256 {
         num += BigUint::from(self.high);
         num <<= 128;
         num += BigUint::from(self.low);
-        write!(f, "{}", num)
+        write!(f, "0x{}", num.to_str_radix(16))
     }
 }
 
 impl FromStr for U256 {
     type Err = ParseBigIntError;
     fn from_str(s: &str) -> Result<Self, Self::Err> {
-        let num = BigInt::from_str(s)?;
-        let num_big_uint = num.to_biguint().unwrap();
+        let num = if s.len() >= 2 && &s[0..2] == "0x" {
+            BigUint::from_str_radix(&s[2..], 16)
+        } else {
+            BigUint::from_str(s)
+        }
+        .unwrap();
         let mask = (BigUint::from(1u128) << 128u32) - BigUint::from(1u128);
-        let b_low: BigUint = (num_big_uint.clone() >> 0) & mask.clone();
-        let b_high: BigUint = (num_big_uint.clone() >> 128) & mask.clone();
+        let b_low: BigUint = (num.clone() >> 0) & mask.clone();
+        let b_high: BigUint = (num.clone() >> 128) & mask.clone();
 
         let mut low = 0;
         let mut high = 0;
@@ -343,7 +397,7 @@ mod tests {
             high: 0_u128,
         };
         println!("{}", u256);
-        assert_eq!(format!("{}", u256), "12");
+        assert_eq!(format!("{}", u256), "0xc");
     }
 
     #[test]