Calculus, linear algebra, probability theory, mathematical statistics, and stochastic processes mentioned by everyone are the foundations of the foundation and are widely used in various disciplines. I am a math major, but my real hobby is computers. I didn't know who said what when I volunteered. I study computer, so I want to study math with software, physics with hardware, and then apply for math. In the department of mathematics, I did receive training in sensory thinking, but most of the courses I took were not directly related to computers. If you really want to engage in computers, you still need to toss computer courses yourself. There is more practice. In fact, I think mathematics is mainly used when designing, selecting and analyzing algorithms. If you just want to "design" a good program, you may not need much math. But if you want to be a computer scientist or engineer, I'm afraid you still have to study math.