elementary numbers- set with n numbers contains subset that the sum of whose elements is a multiple of n
11817
Proving that every set $A \subset \Bbb N$ of size $n$ contains a subset $B \subset A$ with $n | \sum_{b \in B} b$
30105
Multiples of an irrational number forming a dense subset
134770
For sets $A,B$, $A \cap (B \setminus A) \subseteq \varnothing$
76405
Let n be an even integer. How many different ways can I choose subsets of the set {1,2...,n}
25338
Sum of $n$ integers from set of size $2n-1$ divides $n$
115145
Show that $n-m$ is a multiple of 9 when $n$ and $m$ have same digits
57746
Prove that, for any set of consecutive integers with an odd number of terms, the sum of the integers is always a multiple of the number of terms.
22154
Show that given a set of positive n integers, there exists a non-empty subset whose sum is divisible by n
23764
Proving that $A+A \not\subset 2A $ using a particular definition for sum of sets
2900
How many $3$-subsets of $\{1,2,\ldots,10\}$ contain at least one even and one odd integer?
47123
Suppose that a set has an odd number of elements. Explain why half of the subsets will have an odd number of elements
132605
Finding the number of subsets of a set such that an element divides the succeeding element.
20140
Example of set which contains itself
147013
Subset of a finite set is finite
11967
number of subsets of even and odd
51617
What is the proof that the total number of subsets of a set is $2^n$?
70278
$A\subseteq B\to C\setminus B\subseteq C\setminus A\,$ -- how to prove this?