What number does adding th generally mean? Only a few English words are not prototype plus th, and the rest are prototype plus th. You need to remember some words that are not prototype plus th.
Also remember the English words of numbers. If you really can't remember them, it doesn't matter. Just remember them a few times.
Many words have been remembered and forgotten. In fact, a lot of knowledge in life is the same. Only by repeating this word constantly can we use it well.
So if you want to remember it, you still need to work hard by applying words to real life.