1, according to the definition of the equation, if a=b, then A-C = B-C. Therefore, if we subtract a number less than 0.999 ... for example, 0.000... 1, we will get a number less than 0. However, if we add 0.999 ... to a number greater than it, such as 0.000... 1, we will get a number greater than 1.
2. In addition, according to the definition of infinitesimal, when the difference between two numbers tends to zero, two numbers can be considered equal. Therefore, because the difference between 0.999 ... and 1 is very small (about 0.000... 1), we can think that they are equal. However, some people think that 0.999 ... is not equal to 1.
They think that although the difference between 0.999 ... and 1 is very small, they are still different. These people think that only when two numbers are completely equal can they be considered equal.
The origin of numbers
The origin of numbers can be traced back to ancient civilization. In the early days of human development, people began to try to express quantities with symbols. These symbols can be pictures, words or simple numerical symbols.
The earliest digital symbols can be traced back to ancient Egyptian civilization. The ancient Egyptians used hieroglyphics to indicate quantity. For example, a cake can represent the number 1, a goose can represent the number 2, a crocodile can represent the number 3 and so on. These symbols gradually evolved into a more abstract symbol.
In ancient China, people used arithmetic to represent numbers. Calculation is a tool similar to a stick, and different quantities are represented by different numbers of sticks. Over time, these sticks gradually evolved into digital symbols, such as one bar representing the number 1, two bars representing the number 2, and so on.
In ancient India, people used Indian numerals (also called Arabic numerals), which were imported from India by Arabs. Indian numerals include ten basic symbols such as 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9 and their combinations. These digital symbols are simple and easy to read and write, and are gradually adopted all over the world.