What formulas do primary schools have to memorize?
Calculation formula of perimeter, area and volume of mathematical geometry in primary schools
The circumference of a rectangle = (length+width) ×2 C=(a+b)×2.
Circumference of a square = side length ×4 C=4a
Area of rectangle = length× width S=ab
Area of a square = side length × side length s = a.a = a.
Area of triangle = base × height ÷2 S=ah÷2.
Area of parallelogram = base × height S=ah
Trapezoidal area = (upper bottom+lower bottom) × height ÷ 2s = (a+b) h ÷ 2.
Diameter = radius ×2 d=2r Radius = diameter ÷2 r= d÷2.
Circumference = π× diameter = π× radius× 2c = π d = 2π r
Area of circle = π× radius× radius
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 a cylinder: the surface area of a 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 unchanged. Add and subtract fractions with different denominators, divide first, then add and subtract.
Multiplication of fractions: use the product of molecules as numerator and the product of denominator as denominator.
Division of fractions: dividing by a number is equal to multiplying the reciprocal of this number.
Formulas in primary school mathematics and arithmetic
1. additive commutative law: Two numbers are added to exchange the position of addend, and the sum is unchanged.
2. The law of addition and association: When three numbers are added, the first two numbers are added first, or the last two numbers are added first, and then the third number is added, and the sum remains unchanged.
3. Multiplication and exchange law: when two numbers are multiplied, the position of the exchange factor remains unchanged.
4. Multiplication and association law: When three numbers are multiplied, the first two numbers are multiplied, or the second two numbers are multiplied first, and then the third number is multiplied, and the product remains unchanged.
5. Multiplication and distribution law: When two numbers are multiplied by the same number, you can multiply the two addends by this number respectively, and then add the two products, and the result remains unchanged. Such as: (2+4) × 5 = 2× 5+4× 5
6. Nature of division: In division, the dividend and divisor are expanded (or reduced) by the same multiple at the same time, and the quotient remains unchanged. Divide by any number that is not.
Simple multiplication: multiplication of multiplicand and multiplier with O at the end. You can multiply 1 before o first, and zero does not participate in the operation, and add a few zeros at the end of the product.
7. What is an equation? An equation in which the value on the left of the equal sign is equal to the value on the right of the equal sign is called an equation. Basic properties of the equation: When both sides of the equation are multiplied (or divided) by the same number at the same time, the equation is still valid.
8. What is an equation? A: Equations with unknowns are called equations.
9. What is a linear equation with one variable? A: An equation with an unknown number of degree 1 is called a linear equation with one variable. Example method and calculation of learning linear equation of one variable. That is, an example is given to illustrate that the formula is replaced by χ and calculated.
10. Score: divide the unit "1" into several parts on average, and the number representing such a part or points is called a score.
Formulas of special problems in primary school mathematics
1, encountered a problem.
Meeting distance = speed × meeting time
Meeting time = meeting distance/speed and
Speed Sum = Meeting Distance/Meeting Time
Step 2 catch up with the problem
Catch-up distance = speed difference× catch-up time
Catch-up time = catch-up distance ÷ speed difference
Speed difference = catching distance ÷ catching time
3. Tap water problem
(1) general formula:
Downstream velocity = still water velocity+current velocity
Countercurrent velocity = still water velocity-current velocity
Still water velocity = (downstream velocity+countercurrent velocity) ÷2
Water velocity = (downstream velocity-countercurrent velocity) ÷2
(2) Formula for two ships sailing in opposite directions:
Downstream speed of ship A+downstream speed of ship B = still water speed of ship A+still water speed of ship B.
(3) Formula for two ships sailing in the same direction:
Hydrostatic speed of rear (front) ship-Hydrostatic speed of front (rear) ship = the speed of narrowing (expanding) the distance between two ships.
4. Concentration problem
Solute weight+solvent weight = solution weight.
The weight of solute/solution × 100% = concentration.
Solution weight × concentration = solute weight
Solute weight-concentration = solution weight.
5. Profits and discounts.
Profit = selling price-cost
Profit rate = profit/cost × 100% = (selling price/cost-1) × 100%.
Up and down amount = principal × up and down percentage
Discount = actual selling price ÷ original selling price× 1 00% (discount <1)
Interest = principal × interest rate× time
After-tax interest = principal × interest rate × time × (1-5%)
6, engineering problems
Work efficiency × working hours = total workload.
Total workload ÷ working time = working efficiency
Total amount of work ÷ work efficiency = working hours
1÷ working time = a fraction of the total workload completed in unit time?
1What is the score that can be completed per unit time = working time.