A number multiplied by 13 is more than the original number 108, that is, thirteen times the original number is equal to 108 plus himself. So this number 12 times (13- 1) equals 108, so this number is 108 divided by 12=9.

How to learn math well

As we know, the pain index is inversely proportional to the understanding index, and the more understanding, the less pain. Mathematics is a headache for many students because we lack real understanding in the process of mathematics learning and teaching. The expression framework of our mathematics textbooks has remained basically unchanged for many years, so the learning pain points of students now are similar to those of students 30 years ago.

In other words, it is difficult for us to solve the pain points of mathematics learning in the current mathematics textbooks and reach a real understanding. This is also one of the missions of this book, breaking through the expression framework of current mathematics textbooks and solving the pain points of students' understanding. The following ten chapters (basically covering the main knowledge points of high school mathematics) are trying to do this.

In learning, the opposite of understanding is memory. Memory will bring a kind of pressure to people, just as we will worry that we will suddenly forget the words when we speak on the stage, and we will also worry that our memory is not accurate in the examination room. There are more and more knowledge points and more to remember, and this mental pressure will accumulate.