1, addition, subtraction, multiplication and division are called four operations.
2. In the formula without brackets, if there is only addition, subtraction or multiplication and division, it should be calculated from left to right.
3. There are multiplication, division and addition and subtraction in the formula without brackets, and multiplication and division must be calculated first, then addition and subtraction.
4. If there are brackets in the formula, count the inner side of brackets first, and then the outer side of brackets; The calculation order of the formulas in brackets follows the above calculation order.
I want to test the operation of knowledge point 2 0 (dictation) 100:
1 and "0" are inseparable; ? Letter means: 0 error.
2. Add 0 to a number to get the original number; The letter means: a+0 = a?
3. Subtract 0 from a number to get the original number; The letter means: a-0 = a.
4. The minuend is equal to the minuend, and the difference is 0; Letter: A-A = 0
4, a number multiplied by 0, still get 0; Letter: a×0= 0
5. Divide 0 by any number other than 0 to get 0; The letter means: 0÷a(a≠0)= 0.
Knowledge point three operation method (dictation) I want to test 100 points:
Additive commutative law: A+B = B+A.
Additive associative law: (a+b)+c = a+(b+c)
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? Or? a×(b+c) =a×b+a×c
Expand: (a-b) × c = a× c-b× c? Or? a×(b-c) =a×b-a×c
6. Continuous decrease: a-b-c = a-(b+c)
7. Even division: a ÷ b ÷ c = a ÷ (b× c)
Knowledge point 4 Simple calculation 1 (dictation or self-example) I want to take the test 100:
First, the common multiplication operation:
25×4= 100 125×8= 1000
Second, a simple example of additive commutative law: Third, a simple example of the law of additive association:
50+98+50 488+40+60
=50+50+98 =488+(40+60)
= 100+98 =488+ 100
= 198 =588
4. Examples of multiplication and method of substitution simplification: 5. Examples of multiplication and combination simplification:
25×56×4 99× 125×8
=25×4×56 =99×( 125×8)
= 100×56 =99× 1000
=5600 =99000
Six, including the calculation of additive commutative law and simple association law:
65+28+35+72
=(65+35)+(28+72)
= 100+ 100
=200
7. Simple calculation with multiplicative commutative law and associative law:
25× 125×4×8
=(25×4)×( 125×8)
= 100× 1000
= 100000
Knowledge point 4 Simple calculation 2 (dictation or self-example) I want to take the test 100:
Simple examples of multiplication and distribution laws;
I. Decomposition type II. Combination type
25×(40+4) 135× 12— 135×2
=25×40+25×4 = 135×( 12—2)
= 1000+ 100 = 135× 10
= 1 100 = 1350
Three. Special 1 4. Special 2
99×256+256 45× 102
=99×256+256× 1 =45×( 100+2)
=256×(99+ 1) =45× 100+45×2
=256× 100 =4500+90
=25600 =4590
Verb (abbreviation of verb) is especially 3 VI. Special 4
99×26 35×8+35×6—4×35
=( 100— 1)×26 =35×(8+6—4)
= 100×26— 1×26 =35× 10
=2600—26 =350
=2574
Knowledge point 4 Simple calculation 3 (dictation or self-example) I want to take the test 100:
Simple operation example of continuous subtraction:
528—65—35 528—89— 128 528—( 150+ 128)
=528—(65+35) =528— 128—89 =528— 128— 150
=528— 100 =400—89 =400— 150
=428 =3 1 1 =250
Simple operation example of continuous division:
3200÷25÷4
=3200÷(25×4)
=3200÷ 100
=32
Examples of other simple operations:
256—58+44 250÷8×4
=256+44—58 =250×4÷8
=300—58 = 1000÷8
=242 = 125
Five triangles of knowledge points (items 1 to 13 should be memorized) I want to take the test 100:
1, and the figure surrounded by three line segments (the endpoints of every two adjacent line segments are connected) is called a triangle.
Draw a vertical line from the vertex of the triangle to its opposite side. The line segment from the vertex to the vertical foot is called the height of the triangle, and this side is called the bottom of the triangle. This triangle is only three stories high.
3. The triangle is very stable.
4. The sum of any two sides of a triangle is greater than the third side.
A triangle with three acute angles is called an acute triangle.
6. A triangle with a right angle is called a right triangle.
7. A triangle with an obtuse angle is called an obtuse triangle.
8. Each triangle has at least two acute angles; Each triangle has at most 1 right angles; Each triangle has at most 1 obtuse angles.
9. A triangle with two equal sides is called an isosceles triangle.
10, a triangle with three equilateral sides is called an equilateral triangle, also called a regular triangle.
An equilateral triangle is a special isosceles triangle.
12, and the sum of the interior angles of the triangle is 180.
13, and the sum of the internal angles of the quadrilateral is 360.
14. Two identical triangles can be used to form a parallelogram.
15. Two identical right triangles can be combined into a parallelogram, a rectangle and a big triangle.
16. Two identical isosceles right triangles can be combined into a parallelogram and a square. Large isosceles right triangle.
The meaning and nature of six decimal places (Chapter 7, 10, others should be understood) I want to score 100:
1, decimal counting unit is one tenth, one hundredth, one thousandth ... Write 0. 1, 0.0 1, 0.00 1 ...
2. The progressive rate between every two adjacent counting units is (10).
3. Decimal numbers are decimals, percentiles, thousandths ... The highest digit is decimals. The lowest bit of the integer part is one bit. The propulsion rate of unit and decile is 10.
4. Decimal digit sequence table
Integer part decimal part decimal part
Numbers ...100 billion billion billion billion billion billion billion billion billion billion billion billion billion ...
Counting unit ... one thousandth, one thousandth ...
5. Decimal reading: first read the integer part (according to the original reading method), then read the decimal point, and then read the decimal part. Read the decimal part, the decimal part should read each number in turn, and there are several zeros to read.
6. Decimal writing: first write the integer part (according to the original writing method), then write the decimal point, and then write the decimal part: write the decimal part, and write each number in turn in the decimal part, and write several zeros if there are several zeros.
7. Properties of decimals: Add "0" or remove "0" at the end of decimals, and the size of decimals remains unchanged.
8. Size comparison of decimals: (1) Compare the integer parts first; (2) If the integer parts are the same, compare decimals; (3) When the deciles are the same, compare the percentiles; (4) and so on until the size is compared.
9. Movement of decimal point
Decimal point moves to the right:
Move one place, and the decimal will be expanded to 10 times the original number;
Move two places, and the decimal will be expanded to 100 times of the original number;
Move three places, and the decimal will be expanded to 10 00 times of the original number;
If you move four digits, the decimal number will be expanded to 10000 times of the original number; ……
Decimal point moves to the left:
If you move one place, the decimal will be reduced by 10 times, that is, the decimal will be reduced to the original number;
Move two places, the decimal will be reduced by 100 times, that is, the decimal will be reduced to the original number;
If you move three digits, the decimal will be reduced by 1000 times, that is, the decimal will be reduced to the original number;
If you move four digits, the decimal will be reduced by 10000 times, that is, the decimal will be reduced to the original number; ……
10, commonly used units in life:
Quality:? 1 ton = 1000 kg; ? 1 kg =1000g
Length:? 1km =1000m1decimeter = 10 cm? 1 cm = 10/0mm
? 1 decimeter = 100 mm? 1 m = 10 decimeter = 100 cm = 1000 mm?
Region:? 1 m2 = 100 square decimeter? 1 square decimeter = 100 square centimeter
? 1 km2 = 100 hectare? 1 ha = 1 10,000 m2
Rmb:? 1 yuan = 10 angle? 1 angle = 10 point 1 yuan = 100 point.
1 1, approximate decimal places (rounded):
(1) Keep an integer, indicating that it is accurate to one place, that is, omit the decimal part, depending on the number of decimal places. If the number of decimal places is greater than or equal to 5, advance one place. If it's less than five, give it up.
(2) Keep one decimal place, which means accurate to ten decimal places. It is necessary to omit everything after the first decimal place. At this time, it depends on the second place after the decimal point. If the second decimal place is less than 5, it is completely discarded. On the contrary, we should move forward one by one.
(3) Keep two decimal places, which means it is accurate to 1%, so the part after the second decimal place should be omitted. At this time, look at the third place after the decimal point. If the third decimal place is less than 5, it is completely discarded. On the contrary, we should move forward one by one.
(4) In order to facilitate reading and writing, numbers that are not whole tens of thousands or billions are often rewritten as numbers with units of "tens of thousands" or "hundreds of millions". When the number is rewritten as "10,000", it means that the decimal point is moved four places to the left, that is, the decimal point is placed on the right side of the 10,000 digits, and the word "10,000" is added after the number. When the number is rewritten as "1 100 million", it means that the decimal point is shifted to the left by 8 places, that is, the decimal point is placed to the right of 1 100 million, and the word "1 100 million" is added after the number. Then remove the zeros after the decimal point according to the nature of the decimal point.
Addition and subtraction of seven decimal places in knowledge points (article 65438 +0 recitation) I want to take the test 100:
1, attention should be paid to the addition and subtraction of decimals: the decimal points should be aligned, that is, the digits should be aligned, and there is a 0 at the end of the digits, which should generally be removed.
2. The law of integer operation (and simple method) is also applicable to decimal operation.
I want to get a score of 100:
Advantages of bar chart: directly reflect the quantity.
Advantages of broken-line statistical chart: it can reflect both quantity and increase or decrease of quantity.
In the dotted line statistical chart, the changing trend refers to: rising or falling.
Knowledge Point 9 Mathematics Wide Angle (Dictation) I want to take the test 100:
Planting trees:
1, both ends should be planted: interval number = total length ÷ spacing; ? Total length = spacing × number of intervals;
Tree number = interval number+1; Number of intervals = number of trees-1
2. No planting at both ends: number of intervals = total length ÷ spacing; Total length = spacing × number of intervals;
Number of trees = number of intervals-1; ? Number of intervals = number of trees+1
(2) Sawing wood: number of segments = times+1; ? Times = number of segments-1
Total time = x times each time
(3) Square matrix problem: The outermost layer is: side length × 4-4 or (side length-1) × 4.
The total number of the whole square matrix is: side length × side length.
(four) closed graphics (such as circle, ellipse):
Total length ÷ spacing = interval number; Number of trees = Number of intervals