Consider the function h where $h(x,y) = (x+y,x-y)$, $h : \mathbb N\times \mathbb N\to \mathbb N\times\mathbb N$
120642
Let $g : \Bbb N \times \Bbb N \to\Bbb N \times \Bbb N$ defined as $g(m,n) = (m + n,m - n)$
140440
Proving $(A\times C)\cup(B\times D)\subseteq(A\cup B)\times(C\cup D)$
26861
$a+b=c \times d$ and $a\times b = c + d$
39455
Prove that $(X\times Y)\setminus (A\times B)$ is connected
80209
If $X,Y$ are equivalence relations, so is $X \times Y$
103251
Solution(s) to $f(x + y) = f(x) + f(y)$ (and miscellaneous questions...)
15733
Show that the cardinality of $\mathbb N$ is the same as the cardinality of $\mathbb N \times \mathbb N$
66772
$f(f(x)f(y))+f(x+y)=f(xy)$
55693
The functional equation $ f \big( x - f ( y ) \big) = f \big( f ( y ) \big) + x f ( y ) + f ( x ) - 1 $
70861
$\mathbb P^n\times \mathbb P^m\not\cong \mathbb P^{m+n}$
409
functions satisfying $f(x - y) = f(x) f(y) - f(a - x) f(a + y)$ and $f(0)=1$
109710
Bijection between $\mathbb N \times \mathbb N$ and $\mathbb N$
14975
Functions satisfying $f:\mathbb{N}\rightarrow\ \mathbb{N}$ and $f(f(n))+f(n+1)=n+2$
61666
Proving $ [(\vec{a}+\vec{b})\times(\vec{b}+\vec{c})]\cdot(\vec{c}+\vec{a})=2\vec{c}\cdot(\vec{b}\times\vec{a})$
148668
How to show $A\times (B\cup C) = (A\times B)\cup (A\times C)$
50649
On the existence of a continuous bijection $f\colon [0,1]\to [0,1]\times [0,1]$
154698
Union of Cartesian products: $X \times (Y \cup Z)= (X \times Y) \cup(X\times Z)$