How do you use %tile dice?

@JeremyECrawford @ChrisPerkinsDnD how do you use %tile dice? If it's a 45% chance, does it happen on 45 and under or 45 and over?

— Thomas Byrd (@ThomasRB83) February 23, 2018

Percentile Dice. If you have X percent chance of something happening, you want to roll X or lower on percentile dice. See “Game Dice” in the Player’s Handbook (p. 6) for more about using dice. #DnD https://t.co/b3BVrKIvxy

— Jeremy Crawford (@JeremyECrawford) February 23, 2018