Calculation of time worked

I work on both an iPad and a Mac and my worksheet, stored in iCloud, is accessed on both devices

I should like to create a simple Numbers worksheet where I enter in the first column the time I started a task and in the next column the time I ended it, and for the result, in hours and minutes, to show in the third column. Sometimes the task will start on the evening of one day and end the following day.

Any assistance would be greatly appreciated as to how best to format each column and what formula should be used in the third column to achieve the desired result.

Many thanks.