You can find the problem set and the solutions of the μ-Games here:
– Problem Set – First Edition
– Problem Set – Second Edition
– Problem Set – Third Edition
– Problem Set – Fourth Edition
– Problem Set – Fifth Edition
– Problem Set – Sixth Edition
– Problem Set – Seventh Edition
– Problem Set – Eighth Edition
– Problem Set – Ninth Edition
Do you like to practise more? Take a look a Project Euler. For example this problem:
Starting in the top left corner of a 2×2 grid, and only being able to move to the right and down, there are exactly 6 routes to the bottom right corner.
How many such routes are there through a n×n grid?
source: https://projecteuler.net/problem=15