Excel function ROUNDDOWN
The ROUNDDOWN function makes it possible to round a number down to a specified number of decimal places.
Select the ROUNDDOWN function.
- In the "Number" field, enter the name of the cell to round down.
- In the "Num_digits" field, enter the number of decimal points you would like to round down to.
Click OK.

The number has been rounded down.

To round all the numbers down, you can simply do an AutoFill series.
