All mathematical theorems in primary schools.

1, letter expression:

Algorithm * * *: additive commutative law, additive associative law, multiplicative commutative law, multiplicative associative law and multiplicative distributive law, which should be mastered and applied flexibly on the basis of understanding.

The nature of operation refers to: one number plus the difference between two numbers; One number MINUS the sum of two numbers; One number MINUS the difference between two numbers; The quotient of one number multiplied by two numbers; A number divided by the product of two numbers; The quotient of one number divided by two numbers; The sum of several numbers divided by a number, etc. This part is only used for simple operation.

Algorithms include: four integer algorithms, four decimal algorithms and four fractional algorithms. It is required to master the algorithm on the basis of understanding and be skilled in using it to calculate.

The application of formulas in primary school mathematics mainly focuses on two aspects:

1. The algorithm or property is expressed by a letter formula.

Additive commutative law: A+B = B+A.

Additive associative law: (a+b)+c = a+(b+c)

Multiplicative commutative law: ab=ba

Law of multiplicative association: (ab)c=a(bc)

Multiplication and distribution law: a (b+c) = ab+AC.

2. Formulas for calculating the perimeter, area and volume of geometric shapes

Rectangular circumference: c = 2 (a+b)

Square perimeter: c = 4a

Circumference: c = 2 π r, or (πd)

Rectangular area: S=ab

Square area: s = a2

Area of parallelogram: S=ah

Circular area: S=πr2

Cuboid volume: v = ABC surface area s = 2 (AB+AC+BC)

Cubic volume: V=a3 Surface area s = 6a2.

Cylinder volume: v = π r2h surface area s = 2π RH+2π R2.

In order to make students understand and master the basic knowledge correctly, teachers should study the syllabus carefully, study the teaching materials carefully, correctly understand the depth and breadth of the basic knowledge required by the syllabus, and pay attention to cultivating students' ability while making students understand and master knowledge, which will further promote students' understanding and mastery of knowledge. They complement each other and are inseparable.

Travel can usually be divided into the following categories:

Meeting problems: speed and × meeting time = meeting distance;

Catch-up problem: speed difference × catch-up time = distance difference;

Running water problem: the key is to grasp the speed of water without affecting the time of catching up and meeting;

Downstream speed = ship speed+current speed = ship speed-current speed.

Still water velocity = (downstream velocity+upstream velocity) ÷2 Water velocity = (downstream velocity-upstream velocity) ÷2

(That is to say, as long as there are two of the four quantities: downstream speed, countercurrent speed, ship speed and water speed, the other two can be found. )

Circle stroke: grasp the inconvenient relationship in the round trip.

Proportional application: using proportional knowledge to solve complex travel problems is often tested, but it is not easy to test.

Complex trips: including multiple encounters, trains crossing bridges, two-dimensional trips, etc.

2. Define theorem formula

Area of triangle = base × height ÷2. The formula S= a×h÷2.

Square area = side length × side length formula S= a×a

Area of rectangle = length× width Formula S= a×b

Area of parallelogram = base× height Formula S= a×h

Trapezoidal area = (upper bottom+lower bottom) × height ÷2 Formula S=(a+b)h÷2

Sum of internal angles: sum of internal angles of triangle = 180 degrees.

Cuboid volume = length× width× height formula: V=abh

Volume of cuboid (or cube) = bottom area × height formula: V=abh.

Volume of cube = side length × side length × side length formula: V=aaa.

Circumference = diameter × π formula: L = π d = 2π r

Area of circle = radius × radius× π formula: s = π R2.

Surface (side) area of cylinder: The surface (side) area of cylinder is equal to the perimeter of bottom multiplied by height. Formula: s = ch = π DH = 2π RH.

Surface area of cylinder: the surface area of cylinder is equal to the perimeter of the bottom multiplied by the height plus the area of the circles at both ends. Formula: S=ch+2s=ch+2πr2.

Volume of cylinder: the volume of cylinder is equal to the bottom area multiplied by the height. Formula: V=Sh

Volume of cone = 1/3 bottom× product height. Formula: V= 1/3Sh

Law of fractional addition and subtraction: Fractions with the same denominator are added and subtracted, only the numerator is added and subtracted, and the denominator remains the same. Fractions of different denominators are added and subtracted, first divided, then added and subtracted.

The multiplication of fractions is: use the product of molecules as numerator and the product of denominator as denominator.

The law of division of fractions: dividing by a number is equal to multiplying the reciprocal of this number.

Unit conversion

(1)1km =1km =1000m1m =10 decimeter1decimeter =10 cm/kloc.

(2) 1 m2 = 100 square decimeter 1 square decimeter = 100 square centimeter 1 square centimeter = 100 square millimeter.

(3) 1 m3 = 1000 cubic decimeter 1 cubic decimeter = 1000 cubic centimeter 1 cubic centimeter = 1000 cubic millimeter.

(4) 1t = 1000kg 1kg = 1000mg = 1kg = 1kg。

(5) 1 hectare = 1 ten thousand square meters 1 mu = 666.666 square meters.

(6) 1 liter = 1 cubic decimeter = 1000 ml 1 ml = 1 cubic centimeter.

3. Calculation formula of quantitative relationship.

1. unit price × quantity = total price

2. Single output × quantity = total output