Add time last modified from several workbooks onto one worksheet

[Valhalla822]

I need to have my spreadsheet count work inventory. Each of the 40+ users will have their own workbook and the master will automatically add everyone's inventory together. I want to be able to tell if everyone has their numbers from the current date entered. How can I enter the time last modified 40 or so times in a worksheet?


Thanks

[Valhalla822]

I am just going to include a cell that users will manually type the date.