1. Place the mouse in the blank space of the toolbar above, right click and the symbol bar will appear. Click to load the symbol bar. 2. Click "Insert" in the toolbar above, select "Special Symbol", and then select the mathematical symbol after the box appears. 3. If all other methods fail, please select the "smart ABC" input method, click the "V" key, and then press 1, 2,3 ... to find the symbol you want.