To convert numbers to barcode in Excel, you can use a barcode font. Here are the steps to do it:

1. Download and install a barcode font on your computer. There are many free barcode fonts available online, such as Code 128, Code 39, and UPC-A.
2. Open your Excel sheet and select the cell or cells that you want to convert to barcode.
3. Change the font of the selected cells to the barcode font that you installed. You can do this by clicking on the "Font" dropdown menu in the "Home" tab and selecting the barcode font.
4. Enter the numbers that you want to convert to barcode in the selected cells. The barcode font will automatically convert the numbers to barcode.
5. To test if the barcode is working, you can use a barcode scanner to scan the barcode. If the scanner can read the barcode and display the numbers, then the conversion was successful.

That's it! You have successfully converted numbers to barcode in Excel using a barcode font.