diff --git a/src/set3.rs b/src/set3.rs
index e6ced6f..a3843f1 100644
--- a/src/set3.rs
+++ b/src/set3.rs
@@ -359,50 +359,51 @@ pub fn challenge22() {
 }
 
 pub fn challenge23() {
-    // Once you have "untemper" working, create a new MT19937 generator, tap it for 624 outputs,
-    /*
-    let mut mt = mt19937::MT19937::new();
-    let seed: u32 = rand::thread_rng().gen::<u32>();
-    mt.seed(seed);
-    let outputs: Vec<u32> = (0..624).map(|_| mt.extract_number()).collect();
-    */
-
     fn temper(x: u32) -> u32 {
-        //const S: u32 = 7;
-        //const T: u32 = 15;
-        //const U: u32 = 11;
-        //const B: u32 = 0x9D2C5680;
-        //const C: u32 = 0xEFC60000;
-        //const L: u32 = 18;
+        const S: u32 = 7;
+        // const T: u32 = 15;
+        // const U: u32 = 11;
+        const B: u32 = 0x9D2C5680;
+        // const C: u32 = 0xEFC60000;
+        // const L: u32 = 18;
 
         let mut y = x;
         // y = y ^ (y >> U);
-        // y = y ^ ((y << S) & B);
+        y = y ^ ((y << S) & B);
         // y = y ^ ((y << T) & C);
         // y = y ^ (y >> L);
-        y = y ^ (y >> 24);
         y
     }
 
     fn untemper(x: u32) -> u32 {
         //const S: u32 = 7;
         //const T: u32 = 15;
-        //const U: u32 = 11;
         //const B: u32 = 0x9D2C5680;
         //const C: u32 = 0xEFC60000;
-        //const L: u32 = 18;
+        const M: u32 = 32;
 
         let mut y = x;
-        //y = y ^ (y >> U);
-        //y = y ^ ((y << S) & B);
-        //y = y ^ ((y << T) & C);
-        //y = y ^ (y >> L);
 
-        //  xxxx'yyyy
-        // ^0000'xxxx
-        //  xxxx'zzzz
-        println!("{:#010x}", u32::MAX << 11 );
-        y = (y & 0xffffff00) | (((y & 0xff000000) >> 24) ^ (y & 0x000000ff));
+        // reverse y = y ^ (y >> L); L = 18;
+        // const UPPER_18_BITS: u32 = u32::MAX << (M - 18);
+        // const LOWER_14_BITS: u32 = u32::MAX >> 18;
+        // let mut o = y & UPPER_18_BITS; // upper 18 bits are correct
+        // o |= ((o & UPPER_18_BITS) >> 18) ^ (y & LOWER_14_BITS); // all 32 bits are correct
+        // y = o;
+
+        // reverse y = y ^ ((y << T) & C);
+
+        // reverse y = y ^ ((y << S) & B);
+
+        // reverse y = y ^ (y >> U); U = 11;
+        // const UPPER_11_BITS: u32 = u32::MAX << (M - 11);
+        // const SECOND_11_BITS: u32 = UPPER_11_BITS >> 11;
+        // const LOWER_10_BITS: u32 = u32::MAX >> (M - 10);
+        // let mut o = y & UPPER_11_BITS; // upper 11 bits are correct
+        // o |= ((o & UPPER_11_BITS) >> 11) ^ (y & SECOND_11_BITS); // upper 22 bits are correct
+        // o |= ((o & SECOND_11_BITS) >> 11) ^ (y & LOWER_10_BITS); // all 32 bits are correct
+        // y = o;
+
         y
     }
 
@@ -412,13 +413,19 @@ pub fn challenge23() {
     println!("{:#010x} -> {:#010x} -> {:#010x}", a, b, c);
 
     /*
+    // Once you have "untemper" working, create a new MT19937 generator, tap it for 624 outputs,
+    let mut mt = mt19937::MT19937::new();
+    let seed: u32 = rand::thread_rng().gen::<u32>();
+    mt.seed(seed);
+    let outputs: Vec<u32> = (0..624).map(|_| mt.extract_number()).collect();
+
     // untemper each of them to recreate the state of the generator,
     let outputs = outputs.iter().map(|o| untemper(*o)).collect();
 
-    //and splice that state into a new instance of the MT19937 generator.
-    let mut new_mt = mt19937::MT19937::new();
-    new_mt.splice(outputs);
-    println!("{} {}", mt.extract_number(), new_mt.extract_number());
+    // and splice that state into a new instance of the MT19937 generator.
+    let mut spliced_mt = mt19937::MT19937::new();
+    spliced_mt.splice(outputs);
+    println!("{} {}", mt.extract_number(), spliced_mt.extract_number());
     */
 
     println!("[xxxx] Challenge 23: wip");