"Hundred Thousand Whys" is China's first popular encyclopedia!
China Children's Publishing House published in January 1961. It is not a book, but a work published as a "set". The content is very extensive. It introduces various scientific knowledge in a question-and-answer manner. The text is not long and easy to understand, which is in line with the cognitive style and reading characteristics of young readers.
Since June 1970, the 14 volumes previously published have been revised again, and the 15th to 23rd volumes have been added.
- Why do most of our counting and counting methods are in the decimal system
- Why do electronic computers use the binary system
- How the decimal system and the binary system are converted
- Why the unit of time and angle are both in the 60-bit system
- Why All countries in the world use Arabic digital
- . What is the difference between the reading method and the notation in our country? Does the meaning of
- 0 mean the relationship between the light switch and the light without
- ? It can also be expressed by mathematical formulas. Why are electronic computers so widely used? Why do electronic computers count very fast? Why do electronic computers replace manual stakeouts that are several times the "times" of
- . How to use
- Why is there no least common divisor and greatest common multiple
- why the diameter is doubled, The volume of the ball is increased to 8 times.
- Use the corners on a set of triangle plates to draw how many corners
- can draw without moving the big trees at the four corners of the pond. After the pond can be doubled, will it still be square? The concentration of 920" is how the landlord uses usury to cruelly exploit the peasants'
- how the paper on the surface of the earth is pasted on the surface of the earth
- why the shortest route on the common charts is not a straight line but a curve
- why can you see our country all over the world Why is the first artificial earth satellite
- the larger the satellite orbital inclination, the greater the energy required for launch
- why the period of the artificial earth satellite can not be shortened arbitrarily
- why the higher the artificial satellite, the area where it can be seen at the same time on the earth The bigger
- Why is the double-curved arch bridge used on the approach bridge of the Nanjing Yangtze River Bridge to save the most savings
- A steamer with a certain speed? It takes the same time to go back and forth in still water and a round-trip when there is a flow rate.
- Ship A catches up with the distance traveled by Ship B, Why is
- bigger when going down the water than when going backwards? Why in the multiplication of fractions, we must first convert the mixed number into false fraction
- How to judge whether a number can be divisible by 2, 3, 5, 9 or 11
- Why is the last digit The two-digit square of 5 can be calculated quickly
- Any two-digit square can be calculated quickly
- Why some multiplications can be calculated quickly
- Why are two numbers close to 100, 1,000,... Can I do abacus division?
- Why does the Gregorian calendar have a leap year, and the Xia calendar has a leap month
- does not turn the sun Can you figure out which day is the day of the week?
- Why learn approximate calculations
- What is called a scale?
- Why use a line gauge to divide a line segment or a circle arbitrarily?
- The energy is thinner than the hair
- What method is used to measure the length so that the error does not exceed half a wire? Why use a universal tool microscope to measure the length so that the error does not exceed one thousandth of a millimeter
- How to measure the angle with a sine gauge
- How to calculate the length of a cylindrical object
- How to make a simple and practical distance measuring ruler
- Without a measuring instrument, can you visually measure the distance of a distant object?
- Why can you measure the height of a big tree by using the shadow?
- How to estimate the field Rice yield
- Why know the length and width of the reed mats, you can calculate the volume enclosed by the reed mats
- How to estimate the width of the engineering earthwork before dredging the river channel
- How to calculate the width of the Huangpu River
- How to measure the inner diameter of a very thin pipe
- Why use a rope Around, you can calculate the diameter of the round part
- How to measure the diameter of the incomplete round part
- What is the graph algorithm
- Why the pseudo-prism formula can calculate the volume of various shapes
- Is the square of a number necessarily larger than the original number?
- a2-b2 and (a+b)(ab) Which formula is good?
- minus a negative number, why is it the same as adding a positive number equal to its absolute value? Which one of
- a+b and ab is bigger? What is
- ? Jia Xian triangle
- how to calculate the number of races in the elimination system
- how to calculate the number of races in the single-loop system
- 200-meter race, why is the starting point for the person who runs the outer circle more than the person who runs the inner circle
- why Counting the bottom layer of the stack, you can calculate the total number
- why the wheels are round
- how to use a ruler to draw a regular pentagon
- why use a triangle ruler to draw the circumference of
- without a square, how to draw cleverly How to draw a large arc with a radius of several hundred meters
- How to use a simple method to find the center of gravity of the trapezoid
- How to cut paper to cut out a five-pointed star
- Why bridge or roof brackets often form a triangle
- Why iron fence A light push to close up
- why the zoom can enlarge or reduce the graph
- why the magnifying glass can’t "enlarge" the corner
- why the lathe can process elliptical cylinder
- can the lathe be infinitely variable
- how to calculate the most in a bearing How to put a few balls
- how to measure the outer diameter of the odd tooth milling cutter
- why the factory inspects the product, adopts the method of sampling inspection
- how to blank the 90-degree elbow
- what method is used to blank the most economical raw material
- why use the same arbitrary Quadrilateral waste wood can also be used to pave the floor
- Why plant saplings according to a regular triangle, can plant up to
- Why the nuts used on the machine are always hexagonal
- Why hot water bottles, glass cups, gasoline tanks, suction pipes, etc. are all cylindrical
- Why should the chimney be made into a truncated cone
- Why should the diameter of the bottom of the cylindrical ammonia tank be equal to the height
- What is the "stroke drawing" problem
- How to be a "smart tailor" z 16z
- Where should the wheat harvesting yard be set? How to transfer and transport grain to save freight? Why use the "overall planning method" to speed up the progress of the project
- How to improve the utilization rate of the machine tool
- What is the preferred method
- How to use the "origami method" to experiment
- Why use the number 0.618
when experimenting with "folding paper method"
