User:Bsmntbombdood/sandbox

$x=\sum _{n=0}^{\infty }{\frac {1}{n!}}=\lim _{n\to \infty }{{\frac {1}{0!}}+{\frac {1}{1!}}+{\frac {1}{2!}}+\cdots +{\frac {1}{n!}}}$

$a\not \in B$

$a\not =B$

$x={x|x<1}$