? ? Mathematics review materials for grade four, Volume II, full volume, unit 1-8, knowledge point induction, unit 1, four operations.
1. The meaning of addition and subtraction and the relationship between the parts:
(1) The operation of combining two numbers into one number is called addition.
(2) Adding two numbers together is called addend. The added number is called sum.
(3) The operation of finding the sum of two numbers and one of them is called subtraction.
(4) In subtraction, the known sum is called the minuend. Subtraction is the inverse of addition.
(5) The relationship between the parts of addition: sum = addend+addend = and-another addend.
(6) Subtract the relationship between parts: difference = minuend-minuend.
Subtraction = minuend-difference
? Negative = negative+difference
2. The meaning of multiplication and division and the relationship between the parts.
(1) The simple operation of finding the sum of several identical addends is called multiplication.
(2) The multiplication of two numbers is called a factor. Multiplied numbers are called products.
(3) The operation of finding the product of two factors and one of them is called division.
(4) In division, the known product is called dividend. Division is the inverse of multiplication.
(5) the relationship between the parts of multiplication:
Product = factor × factor
Factor = product ÷ another factor
(6) the relationship between the parts:
Quotient = divider-divider
Divider = Divider
Dividend = quotient × divisor
(7) Division with remainder,
Dividend = quotient × divisor+remainder
3. Addition, subtraction, multiplication and division are called four operations.
4. The order of elementary arithmetic
(1) In the formula without brackets, if there are only addition and subtraction operations or only multiplication and division operations, they should be calculated from left to right;
(2) In the formula without brackets, if there are both multiplication and division and addition and subtraction, it should be calculated first (multiplication and division) and then (addition and subtraction); (Multiply first, then divide, then add and subtract)
(3) For the formula with brackets, count the inside of brackets first and then the outside of brackets.
5. About the calculation of 0
① Add a number to 0, and the result is the original number: a+0=a? 0+a=a
② Subtract 0 from a number to get this number: a-0 = a.
(3) A number subtracts itself, and the result is zero: A-A = 0.
(4) Multiplying a number by 0 results in 0: a× 0 = 0; 0×a=0
⑤0 divided by a non-zero number, the result is 0: 0:0÷A = 0；;
⑥0 cannot be divisible: a÷0= (meaningless)
6. Charter a boat. The solution to the chartering problem: first assume, then adjust.
Unit 2 Observing Object 2
1. Correctly recognize the shapes of objects observed from above, in front and on the left.
2. There is a knack for observing objects. Count a few faces first, and then look at their arrangement. Pay attention when drawing figures, only draw the upper and lower numbers.
When you observe the same object from different positions, you may see the same or different figures.
4. Observing different objects from the same position, you may see the same or different graphics.
Only by observing from different positions can we know an object more comprehensively.
The third unit operation method
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For more details, please see Baidu Library: 202 1 PEP Primary School Grade Four Volume II Mathematics Volume 1-8 Unit Knowledge Point Induction.
It is not easy to organize, please adopt it if it is helpful.