diff --git a/Cargo.lock b/Cargo.lock
index 52c80f3..b2a75c2 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -14,11 +14,24 @@ version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
 
+[[package]]
+name = "getrandom"
+version = "0.2.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c05aeb6a22b8f62540c194aac980f2115af067bfe15a0734d7277a768d396b31"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "wasi",
+]
+
 [[package]]
 name = "isprime"
 version = "0.1.0"
 dependencies = [
+ "num",
  "num-bigint",
+ "rand",
  "thread-priority",
 ]
 
@@ -37,6 +50,20 @@ dependencies = [
  "cfg-if",
 ]
 
+[[package]]
+name = "num"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "43db66d1170d347f9a065114077f7dccb00c1b9478c89384490a3425279a4606"
+dependencies = [
+ "num-bigint",
+ "num-complex",
+ "num-integer",
+ "num-iter",
+ "num-rational",
+ "num-traits",
+]
+
 [[package]]
 name = "num-bigint"
 version = "0.4.3"
@@ -48,6 +75,15 @@ dependencies = [
  "num-traits",
 ]
 
+[[package]]
+name = "num-complex"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "02e0d21255c828d6f128a1e41534206671e8c3ea0c62f32291e808dc82cff17d"
+dependencies = [
+ "num-traits",
+]
+
 [[package]]
 name = "num-integer"
 version = "0.1.45"
@@ -58,6 +94,29 @@ dependencies = [
  "num-traits",
 ]
 
+[[package]]
+name = "num-iter"
+version = "0.1.43"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7d03e6c028c5dc5cac6e2dec0efda81fc887605bb3d884578bb6d6bf7514e252"
+dependencies = [
+ "autocfg",
+ "num-integer",
+ "num-traits",
+]
+
+[[package]]
+name = "num-rational"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0638a1c9d0a3c0914158145bc76cff373a75a627e6ecbfb71cbe6f453a5a19b0"
+dependencies = [
+ "autocfg",
+ "num-bigint",
+ "num-integer",
+ "num-traits",
+]
+
 [[package]]
 name = "num-traits"
 version = "0.2.15"
@@ -68,17 +127,66 @@ dependencies = [
 ]
 
 [[package]]
-name = "thread-priority"
-version = "0.10.0"
+name = "ppv-lite86"
+version = "0.2.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "978519ae4c6891352f964b88da4ab5a3a9b74a40247cda5baee145dae6cd3b71"
+checksum = "5b40af805b3121feab8a3c29f04d8ad262fa8e0561883e7653e024ae4479e6de"
+
+[[package]]
+name = "rand"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
+dependencies = [
+ "libc",
+ "rand_chacha",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_chacha"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
+dependencies = [
+ "ppv-lite86",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.6.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
+dependencies = [
+ "getrandom",
+]
+
+[[package]]
+name = "rustversion"
+version = "1.0.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5583e89e108996506031660fe09baa5011b9dd0341b89029313006d1fb508d70"
+
+[[package]]
+name = "thread-priority"
+version = "0.12.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2ee4429f2c3bbeafa7136ea54d75a5f38b02e4f006c0b310f07e35c3b49eb3e7"
 dependencies = [
  "cfg-if",
  "libc",
  "log",
+ "rustversion",
  "winapi",
 ]
 
+[[package]]
+name = "wasi"
+version = "0.11.0+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
+
 [[package]]
 name = "winapi"
 version = "0.3.9"
diff --git a/Cargo.toml b/Cargo.toml
index 007a68e..600baaf 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -6,8 +6,10 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-num-bigint = { default-features = false, version = "0" }
-thread-priority = "0"
+num = "0.4.0"
+thread-priority = "0.12.0"
+rand = "0.8.5"
+num-bigint= { default-features = false, version = "0.4.3" }
 
 [profile.release]
 lto = true          # Enable link-time optimization
diff --git a/optimize_dependencies.bat b/optimize_dependencies.bat
new file mode 100644
index 0000000..25fb54b
--- /dev/null
+++ b/optimize_dependencies.bat
@@ -0,0 +1,2 @@
+REM This uses cargo-unused-features
+unused-features analyze && unused-features prune --input report.json
\ No newline at end of file
diff --git a/src/is_prime.rs b/src/is_prime.rs
index 6658f0d..632f3e0 100644
--- a/src/is_prime.rs
+++ b/src/is_prime.rs
@@ -1,13 +1,15 @@
 
 
 pub mod prime_utils {
-    use num_bigint::BigUint;
+    use num::{BigUint, One, Zero};
 
-    pub fn log_2(x: BigUint) -> u64 {
+    use crate::primality_test::primality_tests::is_probably_prime;
+
+    #[must_use] pub fn log_2(x: &BigUint) -> u64 {
         x.bits() - 1
     }
     
-    pub fn is_prime(number: &BigUint, g_primes: &Vec<BigUint>) -> bool {
+    #[must_use] pub fn is_prime(number: &BigUint, g_primes: &Vec<BigUint>) -> bool {
         if BigUint::from(1u8) == *number {
             return false;
         }
@@ -23,11 +25,11 @@ pub mod prime_utils {
     
         // number = 2^a - 1
         // a = log2(number + 1)
-        let a = log_2(number+1u8);
-        if BigUint::from(2u8).pow(a as u32)-BigUint::from(1u8) != *number {
-            let mut i = BigUint::from(1u8);
-            let one = BigUint::from(1u8);
-            let zero = BigUint::from(0u8);
+        let a = log_2(&(number+1u8));
+        if BigUint::from(2u8).pow(a as u32)-BigUint::one() != *number {
+            let mut i = BigUint::one();
+            let one = BigUint::one();
+            let zero = BigUint::zero();
             
             let sqrtnum = number.sqrt()+&one; //fake ceil function
 
@@ -41,6 +43,10 @@ pub mod prime_utils {
                 }
             }
 
+            if !is_probably_prime(number,5) {
+                return false;
+            }
+
             loop {
                 i += &one;
                 if number%&i == zero {
@@ -50,6 +56,8 @@ pub mod prime_utils {
                     return true;
                 }
             }
+
+            
         }
     
         // 4 12 194
diff --git a/src/main.rs b/src/main.rs
index ccbc32d..001e1eb 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,9 +1,12 @@
-#![warn(clippy::pedantic)]
+#![warn(clippy::perf)]
+#![warn(clippy::all)]
+
 
 pub mod is_prime;
+pub mod primality_test;
 
 use std::{time::SystemTime,thread, io::Write};
-use num_bigint::BigUint;
+use num::{BigUint, One};
 use crate::is_prime::prime_utils;
 use thread_priority::{set_current_thread_priority,ThreadPriority};
 
@@ -20,14 +23,40 @@ fn p(n: f64) -> f64 {
     )
 }
 
-
-fn main() {
-
-    if set_current_thread_priority(ThreadPriority::Max).is_err() {
-        eprintln!("failed to set thread priority to max");
+fn to_usize(f:f64) -> usize {
+    let rounded_num: i64 = f.round() as i64;
+    if rounded_num >= 0 {
+        rounded_num as usize
+    } else {
+        0
     }
+}
 
-    /* 
+fn to_f64(u:usize) -> f64 {
+    f64::from_bits(u as u64)
+}
+
+fn try_set_thread_priority() {
+    if set_current_thread_priority(ThreadPriority::Max).is_err() {
+        eprintln!("[WARN] failed to set thread priority to max");
+    }
+}
+
+fn write_primes(primes: &[BigUint]) {
+    let mut file = std::fs::File::create("primes.json").unwrap();
+    file.write_all(b"[").unwrap();
+    let mut it = primes.iter().peekable();
+    while let Some(prime) = it.next() {
+        file.write_all(prime.to_string().as_bytes()).unwrap();
+        if it.peek().is_some() {
+            file.write_all(b",").unwrap();
+        }
+    }
+    file.write_all(b"]").unwrap();
+}
+
+
+/* 
     let mut buffer = String::new();
     let stdin = io::stdin();
     print!("please enter the number to check: ");
@@ -43,14 +72,19 @@ fn main() {
         println!("\n{number} is not a prime");
     }
     */
+fn main() {
+    const N:i64 = 100_000;
+    const NU:usize = N as usize;
+    const THREADS: usize = 12;
+    const SPLITTER: u128 = 10000u128;
+
+    try_set_thread_priority();
 
     let sys_time = SystemTime::now();
 
-    const N:i64 = 100_000;
-    const NU:usize = N as usize;
     let nf:f64 = 100_000f64;
-    let nthprime_approx:usize = p(nf*1.02).ceil() as usize;
-    const THREADS: usize = 12;
+    let nthprime_approx:usize = to_usize(p(nf*1.02));
+    
     let workloads = nthprime_approx/THREADS;
 
     let primecache: Vec<BigUint> = vec![];
@@ -61,20 +95,15 @@ fn main() {
         let arcclone = primearc.clone();
         let handle = thread::spawn(move || {
 
-            if set_current_thread_priority(ThreadPriority::Max).is_err() {
-                eprintln!("failed to set thread priority to max");
-            }
+            try_set_thread_priority();
 
-            const SPLITTER: u128 = 10000u128;
             let one_thousand = &BigUint::from(SPLITTER*10);
             let one_hundred = &BigUint::from(SPLITTER);
             let ten = &BigUint::from(10u8);
-            
 
             let work_uint = BigUint::from(workloads);
             let mut number = BigUint::from(i)*&work_uint;
-            let inc = BigUint::from(1u8);
-            // let zero = BigUint::from(0u8);
+            let inc = BigUint::one();
             
             let max = BigUint::from(i+1)*work_uint;
             let mut primecache = vec![];
@@ -83,13 +112,12 @@ fn main() {
                 
                 if prime_utils::is_prime(&number,&primecache) {
                     primecache.push(number.clone());
-                    //println!("Found a prime {} {}",number, primecache.len());
                 }
                 if (&number * one_thousand)/&max/ten == &number/&max*one_hundred {
                     let tried_getting = SystemTime::now();
                     let mut new_primecache = arcclone.lock().unwrap();
                     if SystemTime::now().duration_since(tried_getting).unwrap().as_millis() > 50 {
-                        eprintln!("Waited 0.05+ seconds for lock!");
+                        eprintln!("[WARN] Waited 0.05+ seconds for lock!");
                     }
                     new_primecache.append(&mut primecache);
                     new_primecache.sort();
@@ -133,9 +161,9 @@ fn main() {
 
     let added = NU-primes.len();
     if primes.len() < NU {
-        println!("Less primes than expected!");
+        println!("[INFO] less primes than expected");
         let mut number = BigUint::from(THREADS)*BigUint::from(workloads);
-        let inc = BigUint::from(1u8);
+        let inc = BigUint::one();
         loop {
             number += &inc;
             if prime_utils::is_prime(&number, &primes) {
@@ -153,22 +181,11 @@ fn main() {
 
     assert_eq!(primes.len(),NU);
 
-    println!("primes added: {} | % added: {}% | removed: {}",added,(added as f64)/primes.len() as f64*100.0,removed);
-
+    println!("primes added: {added} | % added: {}% | removed: {removed}",to_f64(added)/to_f64(primes.len())*100.0);
     println!("time: {difference:?}");
-
     println!("writing primes...");
 
-    let mut file = std::fs::File::create("primes.json").unwrap();
-    file.write_all(b"[").unwrap();
-    let mut it = primes.iter().peekable();
-    while let Some(prime) = it.next() {
-        file.write_all(prime.to_string().as_bytes()).unwrap();
-        if it.peek().is_some() {
-            file.write_all(b",").unwrap();
-        }
-    }
-    file.write_all(b"]").unwrap();
+    write_primes(&primes);
 
 
 
diff --git a/src/primality_test.rs b/src/primality_test.rs
new file mode 100644
index 0000000..5c70f5c
--- /dev/null
+++ b/src/primality_test.rs
@@ -0,0 +1,60 @@
+pub mod primality_tests {
+    use num::{BigUint, Integer, One, Zero};
+    use rand::RngCore;
+
+    fn generate_random_biguint(num_bits: usize) -> BigUint {
+        let mut rng = rand::thread_rng();
+        let bytes = num_bits / 8 + 1;
+        let mut buf = vec![0u8; bytes];
+        rng.fill_bytes(&mut buf);
+        BigUint::from_bytes_be(&buf)
+    }
+
+    
+    pub fn is_probably_prime(number: &BigUint, iterations: u32) -> bool {
+        if number <= &BigUint::one() || number == &BigUint::from(4u32) {
+            return false;
+        } else if number <= &BigUint::from(3u32) {
+            return true;
+        }
+        let one = BigUint::one();
+        let mut d = number - &one;
+        while d.is_even() {
+            d /= 2u32;
+        }
+        for _ in 0..iterations {
+            let a = generate_random_biguint((number.bits()-1) as usize);
+            let mut x = mod_exp(a.clone(), &d, number);
+            if x == one || x == number - &one {
+                continue;
+            }
+            let mut continue_loop = false;
+            for _ in 0..(number.bits() - 1) {
+                x = mod_exp(x.clone(), &BigUint::from(2u32), number);
+                if x == number - &one {
+                    continue_loop = true;
+                    break;
+                }
+            }
+            if !continue_loop {
+                return false;
+            }
+        }
+        true
+    }
+    
+    fn mod_exp(mut base: BigUint, ex: &BigUint, modulus: &BigUint) -> BigUint {
+        let mut exp = ex.clone();
+        let mut result = BigUint::one();
+        base %= modulus;
+        while !exp.is_zero() {
+            if exp.is_odd() {
+                result = (&result * &base) % modulus;
+            }
+            base = base.pow(2) % modulus;
+            exp /= 2u32;
+        }
+        result
+    }
+    
+}