One is
1. Use Excel's built-in insert directly.
2. Use the function of software input method, taking sogou input method as an example.
1) Click the cell that needs to be input to enter the input state. And use sogou input method to input.
2) Right click on the calligraphy floating window.
3) Select "Digital Serial Number" in the "Soft Keyboard" menu.
4) Just press and hold "Shift"+"A".