For example, in space experiments, you can't really do experiments with rocket aircraft every time, because the cost is too high for any country to afford. So at this time, system simulation is needed, and simulation experiments are used instead of physical experiments. But with what simulation? Use the model; How to build a model? Of course, mathematics should be used, and modeling requires very high mathematics.

For economics, doing some research also needs to establish some models, and mathematics is also essential ~ ~