diff --git a/main.py b/main.py
index 379f286..74ac913 100644
--- a/main.py
+++ b/main.py
@@ -1,29 +1,37 @@
 def hello_world():
     '''Prints "Hello World!".'''
-    return
+    print("Hello World")
+    return 
 
 
 def sum(a, b):
     '''Accepts 2 numbers as parameters, returns sum of a and b.'''
-    return 0
+    return a + b
 
 
 def sub(a, b):
     '''Accepts 2 numbers as parameters, returns subtraction of a and b.'''
-    return 0
+    return a - b
 
 
 def product(a, b):
     '''Accepts 2 numbers as parameters, returns product of a and b.'''
     # CHALLENGE: use a for loop and your sum function to implement product
-    return 0
+    s = 0
+    for i in range(b):
+        s = sum(s,a)
+    return s
 
 
 def divide(a, b):
     '''Accepts 2 numbers as parameters, returns a divided by b.'''
     # only pass in numbers that are divisible for sake of implementation
     # CHALLENGE: use a while loop and your sub function to implement divide
-    return 0
+    count = 0
+    while (a > 0):
+            a = sub(a,b)
+            count +=1
+    return count
 
 
 def root(num):
@@ -31,7 +39,14 @@ def root(num):
     # only pass in numbers that are perfect squares for sake of implementation
     # leetcode easy
     # CHALLENGE: do not use any built-in Python functions
-    return 0;
+    if num is 0 or num is 1:
+        return num
+    a = 1
+    result = 1
+    while (result < num):
+        a+=1
+        result = a + a
+    return a
 
 
 def main():
diff --git a/main2.py b/main2.py
index 2f6ad21..1615e90 100644
--- a/main2.py
+++ b/main2.py
@@ -2,7 +2,13 @@ def oddOrEven(nums):
     '''Given an unsorted list of numbers, return a list that indicates if the value at each index is odd (0) or even (1).'''
     # EXAMPLE:
     # Given [2, 4, 5, 7, 8, 10], return [1, 1, 0, 0, 1, 1]
-    return []
+    list1 = []
+    for x in nums:
+            if x%2 == 0:
+                list1 += [1]
+            else: 
+                list1 += [0]
+    return list1
 
 
 def mostOccurences(nums):
@@ -10,7 +16,25 @@ def mostOccurences(nums):
     # Hint: use oddOrEven to test function faster
     # Hint: use a map
     # Hint: https://stackoverflow.com/questions/13098638/how-to-iterate-over-the-elements-of-a-map-in-python
-    return -1 
+    uniqueCount = {}
+
+    for num in nums:
+        # Check if key already exists, if so, just add one to count
+        if num in uniqueCount:
+            uniqueCount[num] += 1
+        # Key doesn't exist, set count to 1
+        else:
+            uniqueCount[num] = 1
+
+    answer = 0     # answer to keep track of the key
+    maxCount = 0    # maxCount to keep track of max count we've seen in uniqueCount
+    for k in uniqueCount:
+        if uniqueCount[k] > maxCount:
+            answer = k                    # update answer
+            maxCount = uniqueCount[k]     # update maxCount
+
+    return answer
+
 
 
 def main():
diff --git a/main3.py b/main3.py
new file mode 100644
index 0000000..c5d0351
--- /dev/null
+++ b/main3.py
@@ -0,0 +1,98 @@
+#### INCLUDE ANY IMPORTS YOU NEED HERE, DO NOT PIP INSTALL ANY LIBRARIES ####
+import math
+import random
+import datetime 
+from statistics import mean, median, mode
+import csv
+import string
+def perfect_square(num):
+    '''Return the sqrt of <num> only if <num> is a perfect square, otherwise return -1.'''
+    # Hint: math library
+    number = math.sqrt(num)
+    if((num%math.sqrt(num)==0)):
+        return math.sqrt(num)
+
+    return -1
+
+
+
+def random_num_generator(min, max):
+    '''Returns a random number between min and max inclusive.'''
+    # Hint: random library
+    return random.randint(min,max)
+
+
+def get_today():
+    '''Returns today's date in the format <month> <day>, <year> where month is a string, day & year are numbers.'''
+    # Note: Code must work regardless of today's date
+    # Example: November 19, 2021
+    # Hint: datetime library
+    # Map of month to month
+    month = {
+        1: "January",
+        2: "Feburary",
+        # ...
+        10: "October",
+        11: "November",
+        12: "December",
+    }
+    # Gets date in the format <year>-<month>-<day>
+    today = datetime.datetime.now().strftime("%F")
+    # Split the formatted date by the separate '-'
+    date_obj = today.split('-')
+
+    return month[int(date_obj[1])] + " " + date_obj[2] + ", " + date_obj[0]
+
+
+
+def get_stat(nums, type):
+    '''Returns <type> of an unsorted list <nums>, where type can be mean, median, mode.'''
+    # Example: get_stat([0, 1, 2], "median"), returns 1
+    # Hint: statistics library
+    if type == "mean":
+        return mean(nums)
+    elif type == "median":
+        return median(nums)
+    else: # type is mode
+        return mode(nums)
+
+
+def print_by_profit():
+    '''Print data/sales_records.csv in order sorted by profit.'''
+    # Hint: csv library
+    # Hint: use built-in sort() after parsing csv
+    # Hint: figure out how to print out each row in csv first
+    with open('data/sales_records.csv') as file:
+        # Gets all rows in csv file and put into 2d array
+        data_rows = list(csv.reader(file, delimiter=','))
+
+    # Delete first row because it's just the column titles
+    print(data_rows.pop(0))
+
+    # Sort by profit (last index of each row)
+    data_rows.sort(key=lambda i:float(i[13]))
+
+    # Print each row
+    for row in data_rows:
+        print(row)
+
+
+def main():
+    '''Challenge 3 focuses on using some of Python's built-in functions and libraries.'''
+    # Testing challenge 3
+    print("\nTesting perfect_square")
+    print("EXPECTED:", -1, "\nACTUAL:", perfect_square(24))
+    print("EXPECTED:", 5, "\nACTUAL:", perfect_square(25))
+    print("\nTesting random_num_generator")
+    print("EXPECTED:", "[1, 10]", "\nACTUAL:", random_num_generator(1, 10))
+    print("\nTesting get_today")
+    print("EXPECTED:", "October 26, 2021", "\nACTUAL:", get_today())
+    print("\nTesting get_stat")
+    print("EXPECTED:", 1, "\nACTUAL:", get_stat([0, 1, 2], "median"))
+    print("\nTesting print_by_profit")
+    print_by_profit()
+    # Add any additional test cases if needed
+
+
+if __name__ == "__main__":
+    main()
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