According to addition principle in mathematics, when two identical numbers are added together, the result is equal to twice this number. Take 2000 as an example. When we add two 2000, the result is 4000. The mathematical expression can be clearly expressed as: 2000+2000=4000. This simple calculation proves the correctness of mathematical addition principle, and also illustrates the application of mathematics in daily life.

When we say "22000", we actually mean the sum of two 2000, and the result is 4000.