PowerPoint has an option to nominate slides as 'hidden'. When you have a slide you do not want it to display when presenting, tagging it as a hidden slide tells presenter mode to skip this slide. But standard PowerPoint does not let you skip the hidden slides in the slide numbers sequence.

PPT Productivity's Manage Slide Numbers and Slide Totals feature lets you skip slide numbers on hidden slides in PowerPoint. This means that when in PowerPoint presenter mode, your slide numbers will all appear in sequence (numbering is removed from hidden slids, so there is no skipping of numbers or indication of slides being hidden).

The Manage Slide Numbers and Slide Totals feature displays the option - you can choose to either skip slide numbers on hidden slides or keep the numbers on all slides.