diff --git a/ch8/ch10/hash b/ch8/ch10/hash
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diff --git a/ch8/ch10/hash.rs b/ch8/ch10/hash.rs
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+++ b/ch8/ch10/hash.rs
@@ -0,0 +1,12 @@
+use std::collections::HashMap;
+
+fn main() {
+    let field_name = String::from("field");
+    let field_value = String::from("value");
+
+    let mut map = HashMap::new();
+    map.insert(field_name, &field_value);
+
+    print!("{}", map.get("field").unwrap());
+    print!("{}", field_value);
+}
diff --git a/ch8/ch10/median_int b/ch8/ch10/median_int
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diff --git a/ch8/ch10/median_int.rs b/ch8/ch10/median_int.rs
new file mode 100644
index 0000000..a88b5e6
--- /dev/null
+++ b/ch8/ch10/median_int.rs
@@ -0,0 +1,32 @@
+use std::collections::HashMap;
+
+fn main() {
+    let mut numbers = vec![100, 23, 1, 2, 100, 38, 57, 100, 23, 44, 163];
+    numbers.sort();
+
+    let is_even = numbers.len() % 2 == 0;
+    let median: i32;
+    let mut count = HashMap::new();
+
+    if is_even {
+        let n1 = numbers[(numbers.len() / 2) - 1];
+        let n2 = numbers[numbers.len() / 2];
+        median = (n1 + n2) / 2;
+    } else {
+        median = numbers[numbers.len() / 2];
+    }
+
+    let mut mode: i32 = 0;
+    
+    for num in numbers {
+        let entry = count.entry(num).or_insert(0);
+        *entry += 1;
+
+        if *entry > count.get(&mode).copied().unwrap_or(0) {
+            mode = num;
+        }
+    }
+
+    println!("median: {median}");
+    println!("mode: {mode}");
+}
diff --git a/ch8/ch10/or_insert b/ch8/ch10/or_insert
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diff --git a/ch8/ch10/or_insert.rs b/ch8/ch10/or_insert.rs
new file mode 100644
index 0000000..628b1da
--- /dev/null
+++ b/ch8/ch10/or_insert.rs
@@ -0,0 +1,11 @@
+use std::collections::HashMap;
+
+fn main() {
+    let mut scores = HashMap::new();
+    scores.insert(String::from("Blue"), 10);
+
+    scores.entry(String::from("Yellow")).or_insert(50);
+    scores.entry(String::from("Blue")).or_insert(50);
+
+    println!("{scores:?}");
+}
diff --git a/ch8/ch10/overwrite b/ch8/ch10/overwrite
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diff --git a/ch8/ch10/overwrite.rs b/ch8/ch10/overwrite.rs
new file mode 100644
index 0000000..2b7d344
--- /dev/null
+++ b/ch8/ch10/overwrite.rs
@@ -0,0 +1,11 @@
+use std::collections::HashMap;
+
+fn main() {
+    let mut scores = HashMap::new();
+
+    scores.insert(String::from("Blue"), 10);
+    scores.insert(String::from("Blue"), 25);
+
+    println!("{scores:?}");
+}
+
diff --git a/ch8/ch10/pig_latin b/ch8/ch10/pig_latin
new file mode 100755
index 0000000..7edf6ad
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diff --git a/ch8/ch10/pig_latin.rs b/ch8/ch10/pig_latin.rs
new file mode 100644
index 0000000..8e6a691
--- /dev/null
+++ b/ch8/ch10/pig_latin.rs
@@ -0,0 +1,22 @@
+fn main() {
+    let vowels = vec!['a', 'e', 'i', 'o', 'u'];
+    let words = vec!["flow", "fool", "dick", "cock", "sex", "ape", "eel", "apple", "addicted", "ore"];
+
+    for word in words {
+        let c = word.chars().next().unwrap();
+
+        let mut adj = format!("-{c}ay");
+
+        for vowel in vowels.iter() {
+            if c != *vowel {
+                continue;
+            }
+
+            adj = String::from("-hay");
+            break;
+        }
+
+        let w = String::from(word) + &adj;
+        println!("{w}");
+    }
+}
diff --git a/ch8/ch10/update_old b/ch8/ch10/update_old
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diff --git a/ch8/ch10/update_old.rs b/ch8/ch10/update_old.rs
new file mode 100644
index 0000000..3f5a3df
--- /dev/null
+++ b/ch8/ch10/update_old.rs
@@ -0,0 +1,13 @@
+use std::collections::HashMap;
+
+fn main() {
+    let text = "hello world wonderful world";
+    let mut map = HashMap::new();
+
+    for word in text.split_whitespace() {
+        let count = map.entry(word).or_insert(0);
+        *count += 1;
+    }
+
+    println!("{map:?}");
+}
diff --git a/ch8/ch10/usrmgt b/ch8/ch10/usrmgt
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diff --git a/ch8/ch10/usrmgt.rs b/ch8/ch10/usrmgt.rs
new file mode 100644
index 0000000..ea09da5
--- /dev/null
+++ b/ch8/ch10/usrmgt.rs
@@ -0,0 +1,63 @@
+use std::io;
+use std::collections::HashMap;
+
+fn main() {
+    let mut departments: HashMap<String, Vec<String>> = HashMap::new();
+
+    loop {
+        let mut input = String::new();
+        io::stdin().read_line(&mut input).unwrap();
+
+        let words: Vec<&str> = input.split_whitespace().collect();
+
+        if words.is_empty() { continue; }
+        
+        match words[0].to_lowercase().as_str() {
+            "add" => {
+                // Format: add [name] [department]
+                if words.len() >= 3 {
+                    let v = departments.entry(String::from(words[2])).or_insert(Vec::new());
+                    v.push(String::from(words[1]));
+                }
+            },
+            "del" => {
+                // Format: del [name] [department]
+                if words.len() >= 3 {
+                    let v = departments.entry(String::from(words[2])).or_insert(Vec::new());
+                    let mut idx: Option<usize> = None;
+
+                    for (i, who2) in v.into_iter().enumerate() {
+                        if who2 == words[1] {
+                            idx = Some(i);
+                            break;
+                        }
+                    }
+
+                    match idx {
+                        Some(x) => { v.remove(x); () },
+                        None => (),
+                    };
+                }
+            },
+            "ls" => {
+                if words.len() == 1 {
+                    println!("{departments:?}");
+                }
+                if words.len() >= 2 {
+                    let dpt = String::from(words[1]);
+                    let ppl = departments.entry(dpt.clone()).or_insert(Vec::new());
+                    ppl.sort();
+
+                    println!("The following people are in the {} department:", dpt);
+
+                    for pp in ppl {
+                        println!("{pp}");
+                    }
+                }
+            },
+            _ => println!("Unknown command"),
+        }
+
+        println!("");
+    }
+}