Day 20 – Python Standard Library

Project: Build a “Lotto Generator & Date Calculator”

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Learning Goal

Learn how to use Python’s built-in standard libraries—math, random, datetime, time, and os—by solving real problems in one mini project:
a lotto number generator and a date calculator that performs time-based operations.

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01. Problem Scenario

You want to build a small program that can:

1. Generate random lotto numbers.

2. Calculate and display important date information (today, tomorrow, or a specific future date).

3. Save and manage data files automatically.

This project will help you see how Python’s built-in modules simplify common real-world tasks.

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02. Step 1 – Mathematical Operations with math

You need to calculate things like circle areas or factorials.
Instead of writing custom formulas every time, Python’s math module does the job instantly.

import math

# Calculate circle area
r = 5
area = math.pi * math.pow(r, 2)
print("Circle Area:", area)

# Calculate factorial
print("5! =", math.factorial(5))

# Round up and down
print("Ceiling:", math.ceil(3.2))
print("Floor:", math.floor(3.9))

Result: You can easily perform complex mathematical calculations with one line.

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03. Step 2 – Generate Random Numbers with random

Now let’s create the lotto generator feature using the random module.

import random

def generate_lotto():
    return sorted(random.sample(range(1, 46), 6))

print("Lotto Numbers:", generate_lotto())

Each time you run it, you get a different 6-number combination from 1 to 45.

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04. Step 3 – Work with Dates Using datetime

Now you want your app to display today’s date, tomorrow’s date,
and calculate days remaining until a target date (e.g., New Year).

from datetime import datetime, timedelta

# Current date and time
now = datetime.now()
print("Today:", now.strftime("%Y-%m-%d %H:%M"))

# Tomorrow
tomorrow = now + timedelta(days=1)
print("Tomorrow:", tomorrow.strftime("%Y-%m-%d"))

# Days until New Year
new_year = datetime(2026, 1, 1)
diff = new_year - now
print("Days until New Year:", diff.days)

Now your app handles both time display and simple date math.

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05. Step 4 – Pause or Measure Time with time

Let’s simulate a loading animation before showing the lotto numbers.

import time

print("Drawing lotto numbers...")
time.sleep(2)
print("Your numbers are:", generate_lotto())

time.sleep() pauses the program for a set number of seconds—useful for animations or rate limiting.

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06. Step 5 – File and Folder Management with os

Finally, save your lotto results to a file using the os module.

import os

# Create folder to store results
if not os.path.exists("results"):
    os.mkdir("results")

with open("results/lotto.txt", "a", encoding="utf-8") as f:
    f.write(f"{datetime.now()}: {generate_lotto()}\n")

print("Lotto results saved to /results/lotto.txt")

os lets your program create and manage folders dynamically.

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07. Step 6 – Combine Everything

Let’s combine all these modules into a single project file.

import math, random, time, os
from datetime import datetime, timedelta

def generate_lotto():
    return sorted(random.sample(range(1, 46), 6))

def show_dates():
    now = datetime.now()
    tomorrow = now + timedelta(days=1)
    print("Today:", now.strftime("%Y-%m-%d"))
    print("Tomorrow:", tomorrow.strftime("%Y-%m-%d"))

def save_result(numbers):
    if not os.path.exists("results"):
        os.mkdir("results")
    with open("results/lotto.txt", "a", encoding="utf-8") as f:
        f.write(f"{datetime.now()}: {numbers}\n")

def main():
    print("Generating your lucky numbers...")
    time.sleep(2)
    nums = generate_lotto()
    print("Your Lotto Numbers:", nums)
    save_result(nums)
    show_dates()
    print("Good luck!")

if __name__ == "__main__":
    main()

Run this file, and you’ll see your results displayed and saved automatically.

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Key Takeaways