How Do I Create a Numbers Project That “autoupdates” the # Of Days?

I want to create a Numbers file that has two columns of cells. The first column, “column one” will have a cell for each individual in our organization. When I create the second column, it will accurately reflect the number of days each individual in column one has been a member of the organization. That’s the easy part. Here’s the hard part. How do I make the second column “autoupdate” the number of days each individual in column one has been a member in our organization?
I don’t know if this important, but I will not have the actual date the individuals in column one joined up. I will only have the current number of days. I can work backwards and figure out the date if need be, but the Numbers file will contain well over 100 individuals.
As an alternative to “autoupdating”, I don’t mind typing in the current date ONCE if doing so will update column two of all 100+ individuals.
TIA!
JP
MBP 2015, MacOS 10.13.2, Numbers 5.3
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JerryP