Easy method calculations have those methods 5

- Addition and subtraction are easy to calculate.

Teach you a simple algorithm for addition and subtraction within 10,000.

Addition and subtraction operations within 10,000, if the number is close to the whole hundred, when the whole thousand, you can try to use a simple method, as long as the operation.

Pay attention to the following four tips:

1. Subtract if you add more.

For example, in the question 1 2345 198 2345 200 2 2543, 198 is treated as 200 plus 2, so 2 should be subtracted.

Second, the excess subtraction should be added.

Example 2 4953 397 4953 400 3 4556 In this question, 397 is subtracted as 400, and 3 is subtracted, so 3 is added.

Third, add less and then add more.

For example 3 3689 503 3689 500 3 4192, add 503 as 500, and add 3 less, so add 3.

Fourth, reduce the reduction and then make up the reduction.

For example, in the question 4 7568 404 7568 400 4 7164, 404 is subtracted as 400, and 4 is subtracted, so 4 is subtracted.

Friend, your question is a bit strange and unacceptable. Please be specific.

Commutative law, associative law, distributive law.

Tell you a very practical put, within 100 two equal mantissa is 5 numbers multiplied, such as 25 * 25, with 2 times 3, to get 6, followed by 25, that is, 625; For example, 65*65, use 6 times 7 to get 42, and add 25 to the back, that is, 4225, such as 95*95, use 9*10 to get 90, and add 25 to the back, that is, 9025.

To sum up, multiply the number by 1 greater than it by the ten digits, and add 25 to the answer.

There are several ways to do this for easy calculations:

Reduced computation: Reduces the amount of computation to a simpler form by reducing the amount of computation. For example, a long string of numbers can be split into smaller strings of numbers and computed one by one.

Reverse thinking: Reverse thinking is used to solve computational problems in reverse. For example, a multiplication problem can be solved by division.

Approximate Standby Allocation Calculation: The approximate calculation method is used to approximate a complex calculation problem into a simple approximate value. For example, round a long string of numbers to an integer.

Linearized calculation: Converts a nonlinear calculation problem into a linear calculation problem to facilitate the calculation. For example, to transform a squared calculation problem into a multiplication calculation problem.

Use the rules: By observing the rules in the calculation problem, find out the middle of some simple calculation methods to reduce the amount of calculation. For example, for a multiplication problem, if one of the numbers is a power of 2, the shift operation can be used to calculate it.

As follows:

First disturbance 2) (34-27) 5

Easy calculation:

1. In the same level of operation trillion rent, you can arbitrarily exchange the number of guess the position, but you must exchange it together with the previous symbols. (Addition or Multiplication Commutative Law).

2. In the same level operation, the parentheses can be directly added after the plus sign or the multiplication sign to remove the parentheses. Add parentheses after minus and division signs, remove parentheses, and change the number inside the parentheses. (Addition or Multiplication Associative Law).

3. Make up one method, make ten methods, make up a hundred methods, make up a thousand methods: "Nine in the front, ten at the end".

Must remember: 25 find 4 to make 100, 125 to find 8 to make 1000. (Rounding up thoughts).

The details are as follows:

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 clever and 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 becomes x, it can also be easily calculated by using the multiplicative finger slow associativity.

Multiplicative distributive property.

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. On the contrary, axb+axc=ax(b+c) is called the inverse of the multiplicative distributive property (also called extracting the common divisor), especially when a and b are complements.

There are also additions that are used when taking annihilation, such as a+b+c, b and c are complements to each other, you can combine b and c, and then multiply 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 to 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.

The commutative law of multiplication.

The multiplicative commutative law is used to swap the positions of individual numbers: a b = b a additive commutative law.

The additive commutative property is used to swap the positions of individual numbers: a+b=b+a, the additive associative law.

a+b）+c=a+（b+c）

50 easy and error-prone calculations:

28) Jing Youpei 99 64+64

Grinding 47) 63 8 + 91 63 + 63

The Simple Calculation Bright Method is a method that makes calculations simple by using the laws of operation and the fundamental properties of numbers. It can simplify calculations by means of a variety of methods, such as moving with signs, combining laws, multiplication and distribution laws, rounding methods, splitting methods, and dividing by clever variations into multiplication. Simple calculation methods can make complex calculations easy, saving time and effort.

There is no easy algorithm, only the phasor method is used to solve it step by step.

Solution: us (phasor) = 150 2 0° = 75 2 0°V, =100rad s.

xl=ωl=100×6/1000=。

From this, the phasor model of the circuit is obtained as above

IR (Phasor) = US (phasor) r = 75 2 0° 15 = 5 2 0° = 5 2 (a).

il(phasor)=us(phasor) jxl=75 2 0°. IC = US (phasor bond cancellation) (JXC) = 75 2 0° 125 -90° =.

According to KCL: I (phasor) = IR (phasor) + IL (phasor) + IC (phasor) = 5 2-J125 2+.

So: i(t)= a).

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Simple Calculation] Simple method calculation is referred to as simple operation, which is to use the law of operation or the nature of operation, and skillfully use the characteristics between special numbers to make clever calculations.

The multiplicative distributive law is: the sum of two numbers is multiplied by one number, first multiply them with this number separately, and then add them together, the product does not excite the divination change, that is: (a+b) c=a c+b c vice versa: a c+b c=(a+b) c

Calculation method: 1. Use the law of operation. The commutative and associative properties of addition, and the commutative, associative, and distributive properties of multiplication, can be used to make calculations easier.

2. Decomposition factors. Some special numbers can be multiplied to get integers, such as 25 and 4, 125 and 8, etc., and when we encounter these numbers, we can find a way to turn them into numbers that can get integers.

3. Digital deformation. Some of the numbers in the column formula can't be used in the easy way, but we can use the easy way after deforming some numbers, and then we have to deform the numbers.

4. Equal difference series. In some cases, the difference between adjacent numbers is the same, so we can use the equation of the equal difference series.

5. Set up a noisy manuscript number method. In some equations, some numbers are the same, but the formula is relatively long, so we can set the equation composed of the same number as a letter, and then replace the corresponding number in the formula with a letter, and then calculate, which is much simpler.

6. Rounding method. Some decimals are very different from integers, and they have regularities, which we can make up whole numbers to calculate.

7. Splitting method. The splitting method is to split a number into several numbers for the convenience of calculation. This requires mastering some "good friends" such as: 2 and 5, 4 and 5, 2 and, 4 and, 8 and so on. Be careful not to change the size of the number in the split.

Simple calculation, the steps of the calculation are as follows, eight out of nine minus one fifth plus one ninth, equal to eight out of nine plus one ninth and then minus one-fifth, equal to 1-fifth, equal to five out of five minus one-fifth, equal to four out of five, so the final result of this question is 4 5

When doing this problem, if you follow the order, then you must first divide 1 5 and 1 9 into numbers, and then the denominator remains the same, and the points are subtracted, which will be very troublesome. Using the simple method, because 8 9 and 1 9 have the same denominator, he said that the sum of two fractions is equal to an integer one, so that when the fractions are subtracted, it will be easier to dig the score. Years of fissure imitation.

Therefore, when calculating fractions, do not rush to calculate, but look at adding and subtracting the same denominator first, and then adding and subtracting other fractions, so that the calculation will make the calculation process simpler.

The number A = 4/4 of the number B is 5Let A = 1 B = 1 (1 1/4) = 4/5 so. Number B is 1-4/5 less than number A = 1/5

Number A = 5/4 of the number B

The Law of Division:

1. The divisor is a single number, and the division of integers is high. The divisor looks at one by one.

One is not enough to see two, except which businessman which one.

The remainder is smaller than the divisor and is not enough to quotient a zero placeholder.

2. The divisor cover is a two-digit division rule, and the integer division starts from a high position. The divisor is two to see two digits.

Two is not enough to see three, except which businessman.

The remainder is smaller than the divisor and is not enough to quotient a zero placeholder.