I've encountered what appears to be a bug in both Excel for Mac 14.6.1 and 15.19.1.

When you format a cell to be a number (no decimals), and then paste a credit card number in that cell, and hit return/enter, it deletes the last digit and replaces it with a "0".

So for example, 1234567891234567 shows up as 1234567891234560.

or 123456789123456789 shows up as 123456789123456000.

The same thing happens if you type the number in to the cell.

Obviously, I can circumvent if I set it up as a text field by typing '1234567891234567.

Does anyone know why this occurs?

John