How can 1+1=3 be possible?
39908
Finding the error in this proof that 1=2
142994
How to show $\sum_{i=1}^{n} \binom{i}{2}=\binom{n+1}{3}$?
140359
Can the sum of finitely many inverses of distinct odd integers $\geq 3$ be 1?
114074
Intuitive/Visual proof that $(1+2+\cdots+n)^2=1^3+2^3+\cdots+n^3$
20878
If $(a,b)=1$ then prove $(a+b, ab)=1$.
4340
Why does $1+2+3+\cdots = -\frac{1}{12}$?
91506
If $\gcd(a,b) = 1$ then $\gcd(a,a + b) = 1$
60738
If 4n+1 and 3n+1 are both perfect sqares, then 56|n. How can I prove this?
149976
What is "magic" about the combination of addition and multiplication in formal arithmetic?
78569
Besides the $3x + 1$ problem, for which similar problems are still unresolved regarding trayectory?
2251
Can someone give me a hint on how to prove this?
30261
How can I find all integers $x≠3$ such that $x−3|x^3−3$
65648
Different ways to come up with $1+2+3+\cdots +n=\frac{n(n+1)}{2}$
74682
How should I solve combination addition like this?
151308
Is it possible to turn infinite sums into infinite products?
91105
For every $n\ge3$ there exists $n$ different integers $a_1,...,a_n$ so that $\frac{1}{a_1}+\frac{1}{a_2}+...+\frac{1}{a_n}=1$
66317
How to solve $z^3+z+1=0$?