1. Consecutive Days Logins: Given a table logins with columns user_id and login_date, find users who logged in on two consecutive days.

2. Users with All Activities: Given a table activities with columns user_id and activity, find users who have performed all three activities: 'login', 'purchase', and 'logout'.

3. Ranking Products by Price: Given a table products with columns product_id and price, rank the products by price without using the RANK() function.

4. Second Highest Salary: Given a table employees with columns employee_id and salary, find the second highest salary.

5. Duplicate Email Addresses: Given a table users with an email column, find all email addresses that appear more than once.

1. SQL Query for Top N Records: Write an SQL query to fetch the top 5 employees with the highest salaries from an employees table with columns employee_id, name, and salary.

2. SQL Query for Aggregate Function: Write an SQL query to find the average salary of employees in each department from a table employees with columns department_id, employee_id, and salary.

3. Python Function for Factorial: Write a Python function to compute the factorial of a given number.

4. Python List Comprehension: Write a Python one-liner using list comprehension to create a list of squares of the first 10 natural numbers.

5. Python String Manipulation: Write a Python function to reverse a given string.

Given two strings s1 and s2, write a Python function to check if s1 is a rotation of s2. Provide an explanation and the solution.

Design a rental car service. Your solution should include considerations for the following aspects:

1. Database Schema: Outline the schema for storing information about cars, rentals, and customers.
2. Microservices Architecture: Describe the microservices that would be necessary for this system.
3. API Endpoints: List key API endpoints for managing car rentals, including adding a new rental, returning a car, and checking car availability.
4. Scalability: Discuss how you would ensure the system scales to handle a large number of rental transactions.

Given two data sets, build a Python application to combine the data and post the combined data into an API. Describe the approach and provide a sample implementation.

Given a data set of 60 million records and an O(n) computation that takes 2 weeks to complete on a single computer, how would you accelerate the processing time to be completed within 24 hours? Describe your approach and the technologies you would use.

1. MapReduce Random Lines from Large Log Files: Using the MapReduce framework, how would you get X amount of random lines from large log files?

2. Managing a Pool of IPs: Describe how you would design a system to manage a pool of IP addresses, ensuring efficient allocation and deallocation.

3. Rotated Array Search: Given a rotated sorted array, write a Python function to search for a target value. Explain your approach and provide the solution.

Implement a function in Python to calculate the square root of any given number up to 2 decimal points precision. Then, optimize the function and implement a caching mechanism to eliminate redundant calculations. Provide an explanation and the solution.