When working with data from .csv files in Excel that includes numbers with multiple decimal places, take special care to make sure none of the decimal places are cut off.
If you have an Excel spreadsheet with differing decimal places in a column of numbers, and the column is not formatted to display all of the decimal numbers:
. . . when the file is saved to a .csv file, the undisplayed decimals will be dropped.
If you have an existing .csv file which has numbers with varying numbers of decimal places, which is opened, edited, and saved in Excel:
. . . some of the decimal places may be dropped when the file is opened in Excel again, and the numbers rounded up: