7. Our Ten Numbers
1) Numbers are the most abstract encoding. Early numeral systems: Roman numerals (multiplication and division are complicated) - Ancient Greek numeral system (the ancient Greeks were famous for geometry) - Indo-Arabic numeral system (today's Arabic numerals)
2) The advantages of Arabic numerals: First, it is related to position. Different positions have different numbers, such as 100 and 1000; second, 10 and 0 are special symbols, of which 0 is the most important invention in the history of mathematics, which simplifies the number system. Very complex operations, especially multiplication and division algorithms.
8. Alternatives to Ten
1) Numbers can be represented in decimal, octal, and binary (addition, subtraction, and multiplication can be performed with each other, and they can be interchanged with each other). There are only 0 and 1 in binary, which can represent the switch, whether the current passes through, and whether the light bulb is on.
2) Binary is closely related to computer.
9. Binary numbers
1) Bit (binary digit-bit): The basic unit that constitutes an information block. The amount of information transmitted by a bit is the least, and any content less than 1 bit is not information at all.
2) Universal Product Code (UPC, commonly known as: barcode, also a binary code; it consists of 30 vertical stripes of different widths, after decoding, there are 12 numbers below the stripes; it is a 95-bit binary code, including the left guard line, Number, middle guard line, number, right guard line. The first number is the number system symbol, 0 represents the conventional UPC, the next five numbers are the manufacturer's code, the last five are the commodity code, and the last number is the modulo check character, used for error checking)
3) Information redundancy: a term in communication theory, meaning that you don’t need to know all the content, just know the key words; but some redundancy is still necessary for error detection, if the code can be easily changed by the customer Then this product coding measure is meaningless.
4) Bits can represent words, pictures, sounds, movies, product codes, film speeds, etc. All you have to do to represent information in bits is to count how many possibilities there are.