Proving that for every integer n that is not a multiple of 2 or 5 there is another integer that is made up of 1s that can be divided by n
27371
A natural number multiplied by some integer results in a number with only ones and zeros
50534
Prove that if $n^2$ is divided by 3, then also $n$ can also be divided by 3.
33786
Proof that a certain fraction is always an integer
5692
Proving that there is a perfect square between $n$ and $2n$
91105
For every $n\ge3$ there exists $n$ different integers $a_1,...,a_n$ so that $\frac{1}{a_1}+\frac{1}{a_2}+...+\frac{1}{a_n}=1$
88982
Prove that for any two sets $A$ and $B$, $A\notin B$ or $B\notin A$
21612
How to prove this form of $n$?
23097
Prove that every number ending in a $3$ has a multiple which consists only of ones.
24954
Prove that there are infinitely many integers of the form $111\ldots111$ that are multiple of $n$.
70282
Help finding a combinatorial proof of $k {n \choose k } = n {n - 1 \choose k -1}$
22367
How do I prove that for every positive integer $n$, there exist $n$ consecutive positive integers, each of which is composite?
124890
Divisibility within a block of natural numbers
85959
How do I prove that among any $5$ integers, you are able to find $3$ such that their sum is divisible by $3$?
157456
All odd primes except $5$ divide a number made up of all $1$s
92057
Prove that for every odd integer n, there is a group...
48051
Proof related to natural numbers
59535
Prove that there exists such a set of $n$ positive integers