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785 these three numbers and decimal point and multiplication sign, which decimal formula can you write
7.5x8=60
7.8x5=39
>What is the number in front of the multiplication sign in the multiplication formula_ Teaching design of the meaning of multiplication and the law of operation
·Teaching objectives: 1. Make students initially understand the meaning of multiplication through specific life situations. 2. Lead to multiplication by adding the same number. Master the writing method, reading method and the name of each part. 3. Cultivate students to find and put forward problems
Letters denote the law of multiplication and omit the multiplication sign
We need to write commutative law, associative law and distributive law
Commutative law: ab = Ba
Law of association: ABC = a (BC)
Distribution law: a (B + C) = AB + AC
RELATED INFORMATIONS
- 1. In a multiplication, if one factor is increased by 5, the product is increased by 100. If the other factor is increased by 4, the product is increased by 120 Can you directly divide 100 by 5 to get 20, and then divide 120 by 4, the answer is 600
- 2. How many multiplication formulas can you write for the whole ten times one digit, Lu 240?
- 3. What kind of multiplication formula can 2 + 2 + 2 + 4 be written?
- 4. How many three digit numbers can these numbers make up
- 5. How many three digit numbers can be made up of 10 numbers from 0 to 9?
- 6. With the 10 numbers from 0 to 9, you can make up the even number of three digits without repetition 1. When the mantissa is 2, 4, 6 and 8, the number of bits combined is 4. Because the hundreds cannot be 0, the number of bits combined is 8, and the number of bits combined is 8 × 8 × 4 = 256 2. When the mantissa is 0, the combination of 100 bits is 9, the combination of 10 bits is 8, and the total number of combinations is 9 × 8 × 1 = 72 Total 256 + 72 = 328 On the basis of this classification, I have a question: why should we take the hundred first, if we take the ten first. Process 1: there are 9 combinations of ten (ten can take 0), and 7 combinations of hundred
- 7. It is known that ABC is a three digit number, and the sum of the other five three digits composed of a, B and C is 2006, The sum of the other five three digits composed of a, B and C is 2006, so the difference between the largest and the smallest of the six three digits is
- 8. Use 1,3,5,7,9 to form a formula of multiplying three digits by two digits, and write the formula of maximum product
- 9. Please fill in the brackets below with the nine numbers 1 - 9 to make the equation true. Each number can only be used once （ ）÷（ ）=（ ）÷（ ）=（ ）（ ）（ ）÷（ ）（ )
- 10. Fill in the multiplication sign or division sign in the nine brackets of the following formula to make the equation true 10 () 9 () 8 () 7 () 6 () 5 () 4 () 3 () 2 () 1 = 64 / 7
- 11. Given that A1 = 9, A3 + A8 = 0 in the arithmetic sequence {a n}, find 1. The general term formula of the sequence {a n} 2. When n is the value, the first few terms of the number weight {a} and Sn take the maximum And find the maximum value
- 12. Use three four five six seven eight six numbers to form two three digit numbers, make the product of these two three digit numbers maximum, how to arrange, and explain the thinking
- 13. Use 0,1,2,3,4,5 to form the number without repetition. (1) how many four digit numbers can be formed; (2) how many four digit numbers can be formed (2) How many four digits can be divided by 5? (3) How many odd and even numbers can be composed of four digits arranged alternately.
- 14. How to make the nine numbers 123456789 into two four digit numbers, one of which is a multiple of the other, and nine digits cannot be repeated This is the homework of grade three in primary school. There are 123456789 nine numbers. One four digit number is multiplied by one one digit number. The other four digit number is nine numbers. It can't be repeated
- 15. How many of the 3 digits without repetition are composed of 1.2.3.4.5.6
- 16. The four numbers 2.3.4.5 can be used to form many four digit numbers without repetition. What is the sum of all these four digit numbers? Decimals
- 17. Use the 10 numbers of 0 and 9 to form an addition vertical
- 18. When he does multiplication, he takes one of the factors 5 as 15, and the product is 140 more than correct. Can you help him Can you work out the correct product
- 19. Observe the arrangement of the following numbers 157, 65, 27, 11, 5, () and fill in the appropriate numbers in brackets
- 20. Please fill in the number 1-9 of the vacancy and find the maximum number