The meaning of the barcode digits at the back of the Beijing Normal University version of the mathem

The appearance of each book is different, and the information of the place of origin is also different, and the barcode is used to identify it and investigate it.

The barcode is divided into 4 parts, from left to right:

1-3 digits: 3 digits in total, e.g. 693, is one of the countries of China. (690--695 are all China's **, distributed internationally).

4-8 digits: a total of 5 digits, such as 69838, representing the manufacturer**, applied by the manufacturer, allocated by the state.

9-12 digits: a total of 4 digits, such as 0001, representing the goods in the factory**, determined by the manufacturer.

The 13th digit: a total of 1 digit, for example, 3, is the check code, according to a certain algorithm, calculated from the first 12 digits.

Take barcode 6936983800013 as an example.

This barcode is divided into 4 parts, from left to right:

1-3 digits: a total of 3 digits, corresponding to the barcode of 693, is one of the national ** in China. (690--695 are all ** in Chinese mainland, distributed internationally).

4-8 digits: a total of 5 digits, corresponding to the barcode of 69838, on behalf of the manufacturer**, applied by the manufacturer, allocated by the state.

9-12 digits: a total of 4 digits, corresponding to the barcode 0001, representing the goods in the factory, determined by the manufacturer.

The 13th digit: a total of 1 digit, corresponding to the 3 of the barcode, is the check code, according to a certain algorithm, calculated by the first 12 digits and obtained.

Formula 13th bit algorithm.

1. Take out the sum of the odd digits of the number, c1 = 6 + 3 + 9 + 3 + 0 + 0 = 21;

2. Take out the sum of the even digits of the number, c2=9+6+8+8+0+1=32;

3. Add the sum of odd digits to "three times the sum of even digits".

4. The single digit of the result: 117 (117%10=7);

5. Subtract the single digit from 10: 10-7=3;

6. Take a single digit for the obtained number (to 10 to remove the remainder) 3%10=3;

This teacher has talked about provinces, regions, cities, counties, and post offices.

Every book has a barcode!

Barcodes are convenient for manufacturers - automated production; Convenient for dealers - to find and manage books; Convenient logistics - transport find!

There are international standards for barcodes, and each barcode must be applied for before use!

Bin stipulates a certain format, with specific information such as country, region, producer, etc.; According to the barcode, you can find its book title, printing manufacturer, author, and so on!

The barcode is generally on the back cover of the book - the last page of the cover of the whole book, and some are printed together with the ** message!

Scan it with your phone.

I feel that I check that this software is okay.

Give the book a serial number, just like your student number.

Basic Fact 1: Two points determine a straight line.

Fact 2: The line segment between two points is the shortest.

Fact 3: There is only one and only one straight line perpendicular to the straight line.

Fact 4: Two straight lines are truncated by a third straight line, and if the isotopic angles are equal, then the two straight lines are parallel.

Fact 5: There is only one and only one straight line parallel to the straight line.

Fact 6: Two triangles with equal sides and their angles are congruent.

Fact 7: Two triangles with equal corners and their edges are congruent.

Fundamental Fact 8: Two triangles with equal sides are congruent.

Fact 9: Two straight lines are truncated by a set of parallel lines, and the resulting corresponding line segments are proportional.

1. Two points to determine a straight line.

2. The shortest line segment between two points.

3. There is only one and only one straight line perpendicular to the known straight line.

4. There is only one straight line parallel to the known straight line at one point outside the straight line 5. The isotopic angle is equal, and the two straight lines are parallel.

6. The three sides correspond to two equal triangles congruence.

7. The two sides and their angles correspond to two equal triangles congruence.

8. The two corners and their edges correspond to two equal triangles congruence.

9. Two straight lines are truncated by a set of parallel lines, and the corresponding line segments obtained are proportional.

What level of textbook is it? Junior high school? High school?