For a number (x), the reciprocal is (1/x)
For a fraction (a/b), the reciprocal is (b/a)
For a whole number (n), write it as (n/1), then flip to (1/n)
For a mixed number, convert it to an improper fraction first, then flip it
For zero, no reciprocal exists
To check, multiply a number by its reciprocal; the product should be (1)