I am using VLOOKUP to find a "time" result from a "height" input, and (in
another condition) the reverse of this.

The input and output cells work in both circumstances, however I must change
the number formatting each time to reflect wether I am inputting (or
returning) a time ("00:00") or a regular integer (0.00).

Is there a function I can use whereby I do not need to change this
formatting...or the formatting changes itself relative to the same condition
as the formula?