The experience of Tao Ti 4 is 10,000, and the experience of 5 is 25,000. 4-5 means 15,000. Washing the Guiyuan Ling Jade once increases 10 points. 15,000 means washing 1,500 Gui Yuan Ling Jade. It just costs 1500YB. You can also increase your experience through the Guiyuan Ling Jade Wash obtained in the game.
Measure it yourself