To do Alt + h 9 on Mac in Excel, download and install Accelerator Keys, then press Option, followed by h, 9.
Command: Decrease Decimals
This is how to do Alt + h 9 on Mac in Excel with Accelerator Keys, the native ribbon and alt key shortcut solution for Mac users who get more done with Excel.
Alt + h 9 removes one decimal place from the number format. Each press shows one fewer digit after the decimal point.