New posts in Inclusion Exclusion

How many ways are there of creating an $8$ character password with a digit, a lowercase letter, and $2$ capital letters?

Combinations of elements from multiple sets with constraints

What is the optimal number of dice to roll a Yahtzee in one roll?

Number of functions $f:\{1,...,n\}\to\{1,...,n\}$ that have $|f^{-1}(\{i\})|=i$ for some $i$

How to find number of integers not divisible by 2 nor 3 in a range?

Prove that $\sum_{k=0}^{\lfloor (n-1)/2 \rfloor} (-1)^k {n+1 \choose k} {2n-2k-1 \choose n} =\frac{ n(n+1)}2 $

The principle of inclusion and exclusion: How many permutations of the set $\{1, 2,. . . , 8\}$ do not leave any even number in its place?

Ways to Arrange 7 things given restrictions

Computing how many distinct digital products are below $10^n$

Told by Professor that this is PIE, but don't see how it's PIE. Help understanding what constitutes the sets, or alternative ways to solve?