CSV Issues with Microsoft Excel
Microsoft Excel has a very annoying and frustrating issue when opening CSV files, it will convert numeric values odd strings like 5.05528E+12
If you are careful you can solve this issue by using the 'format cells' option in Excel e.g. set the format of a column to the appropriate data type that the column contains, for example, you may need to choose 'Number' with no decimals.
Alternatively, rather using Microsoft Excel to edit CSV files consider other options such as using the Freeware CSV Editor ‘CSVed 2.4’ from http://csved.sjfrancke.nl/ this opens and allows edits without changing your data as Excel can.