1L = 1000 ml (ml, ml)
A cubic container whose length, width and height are 1 decimeter from the inside out is exactly 1 liter. 1 litre water weight 1 kg.
The total blood volume of healthy adults is about 4000-5000 ml. Voluntary blood donors generally donate 200 ml of blood each time.
Conditions for enclosing a triangle: the sum of the lengths of two short sides must be greater than the third side.
Triangle has stability, which is used by many objects in life. Such as: herringbone beam, cable-stayed bridge, bicycle frame.
A triangle with three acute angles is an acute triangle. (The sum of the two internal angles is greater than the third internal angle. )
A triangle with right angles is a right triangle. (The sum of the two internal angles is equal to the third internal angle. The sum of the two acute angles is 90 degrees. The two right-angled sides are the bottom and the height of each other. )
A triangle with an obtuse angle is an obtuse triangle. (The sum of the two internal angles is less than the third internal angle. )
Any triangle has at least two acute angles and three heights, and the sum of the three internal angles is 180 degrees.
A triangle with two equal sides is an isosceles triangle, and its two base angles are also equal. It is an axisymmetric figure with an axis of symmetry (just coincident with the height of the base). )
Vertex of isosceles triangle = 180- base angle ×2 = 180- base angle.
The base angle of an isosceles triangle =( 180- vertex angle) ÷2
In mixed operation: multiply first and then divide, then add and subtract. There are both parentheses and brackets. You should count the ones in parentheses first, and then the ones in the middle brackets.
Two groups of parallelograms with parallel opposite sides are called parallelograms. Their opposite sides are equal and their diagonal angles are equal. There can be two different heights from one vertex to the opposite. Bottom and height must correspond.
Parallelogram is easy to deform. Many objects in life take advantage of this feature. Such as: (electric retractable doors, iron sliding doors, elevators) draw a parallelogram into a rectangle, with the perimeter unchanged and the area changed. Parallelogram is not an axisymmetric figure.
A quadrilateral with only one set of parallel sides is called a trapezoid. A trapezoid with two equal waists is called an isosceles trapezoid, and its two bottom angles are equal, which is a symmetrical figure with an axis of symmetry.
Multiplicative commutative law: a×b=b×a
Law of multiplicative association: (a×b)×c=a×(b×c)
Multiplication and distribution law: (a+b)×c=a×c+b×c
Graphic translation, first translate the key points to the designated places, and then connect the points.
Rotation of the figure, first rotate the key edge to the specified place, and then connect the lines. (No matter translation or rotation, the basic graphics cannot be changed. )
4×3= 12, or 12÷3=4. Then 12 is a multiple of 3 and 4, and 3 and 4 are factors of 12.
The minimum factor of a number is 1, the maximum factor is itself, and the number of factors of a number is limited. For example, the factors of 18 are: 1, 2,3,6,9, 18.
The minimum multiple of a number is itself, and there is no maximum multiple. The multiple of a number is infinite. For example, the multiple of 18 is: 18, 36, 54, 72, 90. ...
The largest factor of a number is equal to the smallest multiple of this number.
Numbers that are multiples of 2 are called even numbers. (Units are numbers 0, 2, 4, 6 and 8)
Numbers that are not multiples of 2 are called odd numbers. (The unit number is 1, 3, 5, 7, 9)
The sum of the digits of a number is a multiple of 3, and this number is a multiple of 3. (For example, the sum of the digits of 453 is 4+3+5= 12. Because 12 is a multiple of 3, 453 is also a multiple of 3. )
Since it is a multiple of 2 and 5, the number in the unit must be 0. (For example: 10, 20, 30, 40 ...)
A number with only 1 and its own two factors is called a prime number. (or prime numbers) such as 2, 3, 5, 7, 1 1, 13, 17, 19...2 are unique even prime numbers.
A number has other factors besides 1 and itself, which is called a composite number. Such as: 4, 6, 8, 9, 10 ...
1 is neither prime nor composite, because the factor of 1 is only 1: 1.
Goldbach conjecture: Any even number greater than 2 is the sum of two prime numbers. 20=3+ 17、40= 1 1+29
Law of product change:? 9? One factor is reduced by several times, and the other factor is expanded by the same multiple, and the product remains the same.
9? 1 One factor is reduced (or expanded several times), and the product is reduced (or expanded) several times when the other factor remains unchanged.
The changing law of quotient:? 9? The dividend and divisor of 0 are expanded (or reduced) by the same multiple at the same time, and the quotient remains unchanged except 0.
9? The divisor of 1 is expanded (or reduced) several times, and the quotient is also expanded (or reduced) several times with the same divisor.
9? 2 The dividend is unchanged, the divisor is reduced several times (except 0), but the quotient is expanded several times.
The broken-line statistical chart can not only see the quantity, but also clearly see the increase and decrease of the quantity. How to make a broken line statistical chart? 9? 0 fixed point? 9? 1 write data? 9? 2 connection? 9? Write down the date
Commonly used quantitative relations:
Area of a square = side length × side length (S=a×a=a)
Circumference of a square = side length ×4 (C=a×4=4a)
Area of rectangle = length× width (S=a×b=ab)
The circumference of a rectangle = (length+width) × 2c = (a+b) × 2.
Total price = unit price × quantity unit price = total price/quantity = total price/unit price.
Distance = speed × time speed = distance/time = distance/speed
Federation of trade unions = work efficiency × time efficiency = time of Federation of trade unions = time of Federation of trade unions.
Room area = area per block × number of blocks = room area/area per block
Meeting distance = (speed A+ speed B) × meeting time = speed A × time+speed B × time.
Distance = (speed A- speed B) × time = speed A × time-speed B × time.