M20ch03.7z.001 -

: Ensure all numbered segments (M20CH03.7z.001, M20CH03.7z.002, etc.) are in the same folder .

You can use 7-Zip on any computer, including a computer in a commercial organization. You don't need to register or pay for 7-Zip. How to Open and Extract .001 Files - Microsoft Q&A M20CH03.7z.001

: Select "Extract Here" or "Extract to [Folder Name]" . The software will automatically find the subsequent parts and combine them into the final file. Troubleshooting : Ensure all numbered segments (M20CH03