Almost all sheets allow to choose the system of units between SI (international), US (US customary) and SI(US) (both systems shown): to do so, click the cell 'Units:' (top right).
To know a more informative definition of a unit used in a particular cell, click on the cell and the input window will open up; then hover with the mouse on one of the units offered to see a short but more informative explanation.
Click 'Cancel' to close the input window without modifying anything.

Cells in the sheet show up a rounded value for legibility.
If you want to know the calculated value with the highest available precision, click on the cell and the input window will open up: the value that you see is the actual calculated value and you can copy and paste it, if you wish.
Click 'Cancel' to close the input window without modifying anything.

You need to register and log in before doing so.
1) Load the sheet of interest from the public library (or from your private space) in the main window
2) Click 'Tools' in the menu, then 'Actions on sheets'
3) Click 'Copy sheet...': this menu line contains the short name of the sheet and the destination folder
4) If you want a different destination folder, before doing step 2 click in the menu the desired destination folder, then restart from step 2
5) After you click 'Copy sheet...' the sheet in the main window is reloaded with your private copy