=( 100+ 12)x 15
= 1500+ 150+30
= 1680
The fourth grade algorithm uses letters to indicate that the additional question type is 1, the two addends exchange positions, and the sum is unchanged. This is called additive commutative law. It is represented by letters:
a+b=b+a
2. Add the first two numbers, or add the last two numbers, and the sum remains the same. This is the so-called law of addition and association. Expressed in letters: (a+b)+c=a+(b+c).
3. Swap the positions of two factors, and the product remains unchanged. This is called multiplicative commutative law. Expressed in letters: a× b = b× a.
4. Multiply the first two numbers, or multiply the last two numbers, and the product remains unchanged. This is the so-called law of multiplication and association. Expressed in letters: (a×b)×c=a×(b×c).
5. When the sum of two numbers is multiplied by a number, you can multiply it separately and then add it. This is the so-called law of multiplication and division. Expressed by letters: (a+b)×c=a×c+b×c or a×(b+c)=a×b+a×c (note: division has no distribution law).
6. Application of the law of multiplicative distribution: (a-a-b )× c = a× c-b× c
7. Subtraction property: a-b-c=a-(b+c)
8. nature of division: a÷b÷c= a÷c÷b= a÷(b×c)
9. Remember that 25× 4 =100125× 8 =1000.
Fourth grade math, multiplication formula, help me have a look. 24*59+24=24*(59+ 1)=24*60= 1440
125×8 divided by 25×8 How to calculate the fourth grade monthly exam 125×8÷25×8 with the algorithm?
= 125÷25x8x8
=5x64
=64x 10÷2
=640÷2
=320
How to do the multiplication formula 5 * 9 *125 * 6 * 8 5 * 9 *125 * 6 * 8 in the fourth grade of primary school?
=(5×9×6)×( 125×8)
=270× 1000
=270000
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Is there any exercise about algorithm and simple calculation classification in the second volume of fourth grade mathematics? First of all, think carefully and fill in carefully. (Per grid 1 minute, ***25 points)
1, the letters ι, b and c represent the following operation rules:
(1) additive commutative law: _ _ _ _ _ _ _ _ _ _ _; (2) Multiplication and distribution law: _ _ _ _ _ _ _ _ _ _ _ _;
(3) Multiplicative commutative law: _ _ _ _ _ _ _ _ _ _ _; (4) Additive associative law: _ _ _ _ _ _ _ _ _ _ _ _;
(5) Multiplicative associative law: _ _ _ _ _ _ _ _ _ _ _.
2, any two multiplication, exchange two factors, the product is unchanged, this is called _ _ _ _ _ _ _.
3. When adding any three numbers, add _ _ _ _ _ or _ _ _ _ first, and the sum remains unchanged. This is the so-called law of addition and association.
4. When two numbers _ _ _ _ _ _ _ are multiplied by a number, you can add them to this number first _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.
5. If a number is subtracted twice in a row, it is equivalent to subtracting _ _ _ _ _ _ _ from the two subtractions with this number.
6. A number is divisible by several numbers in a row, and the position of any _ _ _ _ _ _ _ divisor remains unchanged. That is \ \ \ \ = _ _ _ _ _ _.
7.45× (20× 39) = (45× 20 )× 39 This is the application of the _ _ _ _ _ _ _ law.
8. To calculate 376+592+24 in a simple way, we must first calculate _ _ _ _ _ _ _ _ _ _, which is based on the _ _ _ _ _ _ _ _ law.
9. According to the algorithm, fill in the appropriate number in □ and the appropriate operator in ○.
( 1)a+(30+8)=(□+□)+8
(2)45×□=32×□
(3)25×(8-4)=□ ×□ ○□ × □
(4)496- 120-230=496-( □ ○□ )
(5)375-(25+50)=375- □ ○ □
Second, sit in the right position. (The serial number of the correct answer is in brackets) (10)
1.49× 25× 4 = 49× (25× 4) This is based on ().
A. Multiplicative commutative law B. Multiplicative distributive law
C. Law of multiplicative association D. Law of additive association
The simple algorithm of 2.986-299 is ().
A.986-300- 1
C.986-200-99 D.986-(300+ 1)
3.32+29+68+41= 32+68+(29+41) This is based on ().
A. additive commutative law B. Additive associative law
C. additive commutative law and associative law D. Multiplicative associative law
4. The laws of multiplication and distribution are used in the following formula ().
a . 42×( 18+ 12)= 424×30
B.a×b+a×C=a×(b-C)
C.4×a×5=a×(4×5)
D.( 125-50)×8= 125×8-50×8
5. The simple algorithm of125 ÷ 25× 4 is ().
a、 125÷(25×4) B、 125×4÷25
c、 125÷5×5×4 D、 125÷5÷5×4
Third, the judge. (Put √ in brackets for the right and × for the wrong) ×)( 10/0)
1、25×(4+8)=25×4+2×58…………………………………………( )
2、(32+4)×25=32+4×25 …………………………………………… ( )
3、 180÷5÷4= 180÷(5×4)……………………………………………( )
4、 125×4×25×8=( 125×8)+(4×25)…………………………… ( )
5.52+83+48=83+(52+48) Only additive commutative law is used in this calculation. ………( )
6、3 1+23+77=3 1+ 100………………………………………………… ( )
7、 136-68+32= 136-(68+32)………………………………………( )
8、4 12+78+22=4 12+(78+22)………………………………………( )
9、 17×99+ 1= 17× 100……………………………………………………( )
10、450×8÷ 100=450× 100÷8………………………………………… ( )
Iv. Calculate the following questions with a simple method (12×3=36 points)
( 1)94+38+ 106+62
(2) 125× 15×8
(3) 25×32× 125
(4) 125÷25×8
(5) 125×48
(6)989- 186- 14
(7)4600÷25÷4
(8) 136× 10 1- 136
(9) 32×37+47×37+2 1×37
( 10)99×77+77
( 1 1) 99×8
( 12) 78×37-37×68
Fifth, solving problems can be simple and easy to calculate. (19)
1, students go to the military region to perform, grade four 1 13, grade five 272, grade six 87. How many people will go in three grades? (3 points)
2. The grain store brought in a batch of rice, including large and small bags 16 bags, large bags of 50 kg and small bags of 25 kg. How many Jin of rice did a * * * bring in? (4 points)
It takes an engineering team a month to dig a canal with a length of 2670 meters. It is known that it excavated1016m in the early stage and 984m in the middle stage. How many meters do you need to dig in order to finish the task on time? (4 points)
The school should make 4800 colorful flags and give this task to 25 classes. There are 4 groups in each class. How many colorful flags should each group make on average? (4 points)
A building has 25 floors, each floor has 24 windows, and each window has 4 pieces of glass. How many pieces of glass are there in this building? (4 points)
Absolutely to your liking, ... tumor jar shed
Additive commutative law: A+B = B+A.
Additive associative law: a+b+c=a+(b+c)
Multiplicative commutative law: a*b=b*a(ab=ba)
Law of multiplicative association: a*b*c=a*(b*c)(abc=a(bc))
Multiplication and distribution law: (a+b)*c=ac+bc((a+b)c=ac+bc)
Simple. I can't play.
How to let students master the operation law of the fourth grade unit? The name is represented by letters.
Additive commutative law a+b=b+a
Additive associative law (a+b)+c=a+(b+c)
The multiplicative commutative law a×b=b×a can also be written as: a× b = b× a or as: ab=ba.
The multiplicative associative law (a×b)×c=a×(b×c) can also be written as: (a× b) c = a (b× c) or: (ab)c=a(bc).
The multiplication and division method (a+b)×c=a×c+b×c can also be written as: (a+b) c = a.c+b.c can also be written as: (a+b)c=ac+bc.
Subtraction association law a-b-c+=a-(b+c)