The number of subsets of $\{1,2,\ldots,10\}$ with three elements that contain at least one even number and at least one odd number.
2900
How many $3$-subsets of $\{1,2,\ldots,10\}$ contain at least one even and one odd integer?
106397
Counting ways to partition a set into fixed number of subsets
102136
How many subsets contain no consecutive elements?
132605
Finding the number of subsets of a set such that an element divides the succeeding element.
156242
As many even numbers as natural numbers.
47123
Suppose that a set has an odd number of elements. Explain why half of the subsets will have an odd number of elements
23097
Prove that every number ending in a $3$ has a multiple which consists only of ones.
28183
Probability of selecting an even natural number from the set $\Bbb N$.
85099
How many subsets of $\mathbb{N}$ have the same cardinality as $\mathbb{N}$?
107964
Simple combinatorics problem.
117414
How would I prove what elements $S_3$ contains, and what its subgroups are?
57822
Number of ways to choose two disjoint subsets of a set
146204
Subsets sharing at most $i$ elements
117658
A set with n elements has 2^n subsets
156319
Show that a group with $|G| = 33$ contains an element of order $3$
69833
Number of elements not equal to their inverses is even number
85817
Show that in any set of $2n$ integers, there is a subset of $n$ integers whose sum is divisible by $n$.