Symbols:Number Theory

$$x\backslash y$$ or $$x|y$$

These symbols mean $$x$$ is a divisor of $$y$$.

$$\backslash$$ is becoming increasingly popular since many mathematicians are of the opinion that $$|$$ is overused, and hence confusing.

The LaTeX symbol for $$x\backslash y$$ is "x\backslash y", and the symbol for $$|$$ is "|".

$$x \nmid y$$

This means $$x$$ is not a divisor of $$y$$.

The LaTeX symbol for $$x \nmid y$$ is "x \nmid y".

This symbol is preferable to $$x\not\backslash y$$ ("x\not\backslash y") and $$x\not|y$$ ("x\not|y") due to the somewhat confusing appearance of these symbols.