Does a non-fraction number have a reciprocal?

Question

As far as I understand from this Wikipedia page, $\frac 73$ is a reciprocal of $\frac 37$;

But can a term "reciprocal" be applied to a non-fraction number?

For example, it would be correct to say:

reciprocal of $\frac 21$ is $\frac 12$

But would it also be correct to say:

reciprocal of 2 is $\frac 12$

?

Answer 1

Yes, every number have a reciprocal, except $0$. It's also called its multiplicative inverse.

Answer 2

Yes. For instance, $\dfrac1{\pi}$ is the reciprocal of $\pi$. $\dfrac1r$ is the reciprocal of $r$ for any nonzero $r\in \Bbb R$.