Find a simple arithmetic problem for the fourth grade. 25

It's not that why do you want so many problems, there are only a few kinds of operation methods, and you can't rely on the sea of questions, tactics, formulas, and algorithms to understand.

Selected Exercises] Detailed Explanations of Answers] Reputation in the scum.

Easy calculations.

Simple calculation is a special kind of calculation, which uses the laws of operation and the basic properties of numbers, so as to make the calculation easy, so that a very complex formula becomes easy to calculate the number.

The most common method used in simple calculations is the multiplicative distributive property. The multiplicative distributive property refers to ax(b+c) = axb+axc, where a, b, c are arbitrary real numbers. Conversely, AXB+AXC=AX(B+C) is called the inverse of the multiplicative distributive law (also known as extracting the common divisor), especially when a and b complement each other, this method is more useful.

There are also times when the associative property of addition is used, such as a+b+c, where b and c are complements to each other, so you can combine b and c and multiply it with a. If the + in the above equation is changed to x, it can also be easily calculated by using the associative property of multiplication.

The associative law of multiplication.

The associative law of multiplication is also a method of doing simple operations, which is expressed by letters as (a b) c = a (b c), and its definition (method) is: multiply three numbers, first multiply the first two numbers, and then multiply the third number; Or multiply the last two numbers first, and then multiply them with the first number, and the product remains the same. It can change the order of operations in multiplication operations, and the multiplication law is not used very much in daily life, mainly in some more complex operations to play a simple role.

1 A has yuan, B has yuan, and they want to buy a soccer ball together, and the price of a soccer ball is twice the sum of their money.

2 How many hours does it take to plough 15 hectares of land in 3 hours with one machine and 5 machines to plough 75 hectares of land?

3 There are 14 boxes of duck eggs in the store, and after selling 250 kilograms, there are 4 boxes and 20 kilograms left, how many kilograms are in each box of duck eggs?

4 Guangming Primary School donated 240 books to students in mountainous areas, 240 books were donated by the fourth grade, twice as many books were donated by the fifth grade as the fifth grade, and 120 more books were donated by the sixth grade than the fifth grade.

5 How many kilograms of rice are more than flour when the grain store brings in 20 bags of rice and 20 bags of flour each, 90 kilograms of rice and 25 kilograms of flour per bag? (Answer in two ways).

6 The length of the two ropes is 1 meter, and after the rice is cut from the first, the second rope is 6 meters longer than the remaining 2 times the first rope How many meters are the two ropes originally long?

1.Students in grades 4 and 5 collect tree seeds, 18 6 kg of tree seeds are collected in grade 4, and kg less than grade 5 is collected in grade 4, how many kg of tree species are collected in total in the two grades?

2.A workshop used to use 2450 kilowatt-hours of electricity per month, after carrying out saving activities, the original one-year electricity consumption can now be used for 2 more months, how many kilowatt-hours of electricity is saved per month on average in this workshop?

49×102－2×49 125×76×8

40 multiplied by 25 480 divided by 32 120 divided by 5 divided by 4

38 times 201 45 times 97 - 7 times 45 21 times 41 minus 21

35 times 22 plus 35 times 36 + 35 times 22 44 times 198 125 times 25 times 8 times 40

95 times 53 plus 53 99 times 125 45 times 101 minus 45

2. Calculate in a simple way.

Got it, you don't want me to solve it at all.

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