I saw a great article today (admittedly on Facebook) on the fact that yes, you do use the Algebra every single day. And that dogs do complex calculus. I love this! Sure, there are actual equations we sometimes make like calculating tip on a restaurant bill, counting billable hours this week, estimating time to completion but there are more subtle ways we use it too and I think really good project managers know these.

1. Knowing what time it is
• We all know that PMs spend a lot of time waiting on a critical completion stage before sending out notices. Good PMs are always aware of the clock and approximating time remaining. This is during meetings, allocated development time, or overall project health, PMPs are great at telling you the current time. The clock doesn't lie. And they will always be quick to tell you that no, you really do only have 4 more days or it'll cost more money.
2. Turning data points into max, min, and mean
• Red flag! Showstopper or minor delay? PMs know projects and they know when things are just a setback or a major rework. Being able to identify outliers is important, and to get outliers you need to define your boundaries of normal. PMs are great at drawing the line and knowing when enough is enough or to hold their breath again.
3. Values to percentages
• How far along is the project if 5/100 things are done? How many of the 42 test cases need to be run before we can do a beta release? PMs are experts at the 80-20 rule and are always looking at how much more than how many. Being able to quickly translate dollar values to profit and convert numbers into meaningful statistics is what makes PMs great.