How to Make Excel Accept 20 Digit Numbers

1. Right-click on the cell in which you want the 20-digit number to appear. Use shift or control to select multiple cells first, if multiple cells will be accepting 20-digit numbers.
2. Click on 'Format Cells...'
3. Choose 'Text' and click 'OK' to exit.
4. Paste or type the 20-digit number into the cell. Every digit will remain unchanged.