1. After opening the ppt document, click "Insert" at the top left.
2. Under the Insert menu bar on the right, find the symbol and click it.
3. In the pop-up symbol setting box, select the font "Ordinary Text" subset and "Digital Form", and Roman numerals will appear. Select one, two, three, click, and then click Insert below to successfully add Roman numerals one, two, and three to ppt.