Maybe read a little bit about the man first.

Atkinson invented double-clicking, the selection lasso, MacPaint, QuickDraw, and HyperCard. When Steve Jobs was asked how many man-years QuickDraw took to develop, he asked Atkinson how long it took him. Atkinson said, "four years" so Jobs responded to the reporter, "Twenty-four man-years." Yes, Jobs was a hype machine for the Mac team, but he (and everyone around him) also knew that one Atkinson year was the equivalent of six typical developer years.

https://www.folklore.org/StoryView.py?project=Macintosh&stor...