How to calculate addition and subtraction quickly, how to calculate addition and subtraction quickly

This has to be calculated by more calculations, and more calculations can be calculated quickly.

1. Arrange your time carefully. First of all, you need to know what you want to do during the week, and then create a schedule of work and rest. Fill in the form with the time you have to spend, such as eating, sleeping, going to class, having fun, etc.

Once these times have been scheduled, a suitable, fixed amount of time is chosen for studying, and enough time must be set aside to complete normal reading and homework. Of course, studying should not occupy all the free time on the schedule, but should always set aside some time for rest, hobbies, and entertainment, which is important for studying. A schedule may not solve all your problems, but it will give you an idea of how to spend your time during the week, so you have plenty of time to study and have fun.

2. Preview before studying. This means that before you start learning, you should take a quick look at the content you want to learn to understand the general content and structure of the learning so that you can understand and digest it in time. Of course, you need to pay attention to the importance and detail, you can spend less time in less important places, and you can slow down the learning process a little bit in important places.

3. Make the most of class time. Students who do well academically benefit greatly from making the most of their time in class, which also means spending less effort after class. In class, you should cooperate with the teacher in a timely manner, take notes to help you remember what the teacher teaches, and it is especially important to actively think independently and keep up with the teacher's thinking.

If you want to learn how to quickly calculate addition, you first need to master certain calculation methods and skills. Because every equation has a fixed calculation method. As long as you master it well, you can easily learn to calculate well.

Fraction addition and subtraction are divided into two cases:

1. The denominator of the fraction of addition and subtraction is the same, in this case, the denominator of the result remains unchanged, the numerator is directly added and subtracted, and the sum or difference of addition and subtraction is the numerator of the result.

2. The denominator of the fraction of addition and subtraction is different, in this case, the addition and subtraction should be made the same denominator first, and then the operation in 1 should be carried out.

General fraction: According to the basic properties of fractions (formulas), the process of converting several fractions (formulas) with different denominators into fractions (formulas) with the same denominator equal to the original fractions (formulas) is called general fractions.

Example: 7 9 and 8 11 are added.

Solution: First pass: 7 9

Add it up:

1. Integer addition: Integer addition is the integer addition method, first make up the whole number and then add the difference, you can calculate it quickly. For example, when calculating 8+7=15, first make up 8 to 108 plus 2 equals 107 minus 2 equals 510 5=15, such as 17 9=26, the calculation program is 17+3=209-3=620+6=26.

2. Complement addition: Complement addition is fast, mainly because there is no trouble of carrying bit by bit. A complement is the sum of two numbers for 101001000 and so on.

8 + 2 = 1078 + 22 = 1008 is the complement of 2, 2 is also the complement of 8, 78 is the complement of 22, and 22 is also the complement of 78. The method of addition using complements is to add 1 to the 10 digits, and subtract the complements to the single digits. For example, 6+8=14 is calculated by adding 1 to the 10th place of 6 to become 16, and then subtracting the complement 2 of 8 from 16 to get 14.

For example, 6 + 7 = 13 first 6 + 10 = 16 and then 16-3 = 13, such as 27 + 8 = 3527 + 10 = 3737-2 = 35, such as 25 + 85 = 11025 + 100 = 125125-15 = 110, such as 867 + 898 = 1765867 + 1000 = 18671867-102 = 1765.

3. The addition of swapping positions: two ten-digit swap positions, there is a quick calculation method: ten digits plus one digit, and one and is double, and is two digits plus row**.

For example, 61 16 77, the calculation program is 6 1 77 is one single number, and the sum is double, that is, two 7, 61 + 16 = 77, and then 83 38 121 The calculation program is 8 3 1111 is a two-digit number, and the two digits are added to 1 1 2 rows **, and 2 is arranged in the middle of 11, and 121 is obtained.

The math addition and subtraction quick calculation tips are as follows:

1. The left hand represents the tenth, and the right hand represents the single digit.

2. The big female finger represents 5 (equivalent to the upper bead of the abacus), and the remaining four fingers represent 1 (equivalent to the lower bead of the abacus).

3. Break 5 addition and subtraction (4 + 3) a, excite the right hand to declare 4 fingers (non-big female finger) b, declare the big female finger, close the tail, ring finger (2 fingers 5-3) if it is plus 1 (4 fingers 5-1).

4. Break 10 addition and subtraction. Practice makes perfect, mathematics is practice, there is no other shortcut. Memorize the decomposition and combination of numbers within 10 and make up 10 plus and make up 10 minus.

It can be mainly used in the form of icons for teaching, memorization and scrutiny. From the table, you can find the rules between numbers and numbers, and between numbers and numbers.

1.Increase the subtraction method. Formula: add the number in front and add the integer of the number added later, minus the difference between the number added and the whole number in the back.

2.Subtract the difference method. Formula: The whole number of the subtraction is subtracted from the subtraction, plus the difference between the subtraction and the integer.

3.Find the sum of just two two-digit numbers with the position of the numbers reversed in the formula: the ten digits of a number plus his single digit multiplied by 11.

4.Find the difference between just two two-digit numbers that are reversed in the position of the number formula: the ten digits of a number minus his single digit multiplied by 9.

5.The head and tail are interchanged, but the middle number is the same three-digit difference formula: the hundred-digit number is reduced to the single digit and multiplied by 9, and then the middle is inserted 9.

6.Find the difference between two complementary numbers Formula: Subtract the middle number (50 for two digits and 500 for three digits) and multiply by 2.

7."Rounding" method formula: first calculate the addition of two numbers, if you can make up the whole number.

Ten, hundreds, thousands, thousands...then calculate first.

8.Arithmetic progression. A string of numbers where the difference between two adjacent numbers is equal is called an equal difference continuous number, also called an equal difference series, such as:

1, 3, 5, 7, 92, 4, 6, 8, 103, 6, 9, 12, 154, 8, 12, 16, 20, etc., are all contiguous continuums.

Formula 1: When the number of contiguous continuities is an odd number, their sum is equal to the middle number multiplied by the number.

Formula 2: When the number of conceivable numbers of equal difference is even, their sum is equal to the sum of the first and last numbers multiplied by half of the number.

9.Benchmark number method. Observe what number is close to the size of each add, then add each addition to the close number, then add the undercounted and subtract the overcounted.

10.Clever calculation in subtraction: Add up several subtractions that are "complementary" to each other, and then subtract from the subtracted number.

First subtract those minuses that have the same mantissa as the minus.

The quick calculation tips for addition are as follows:1. Increase the difference reduction method.

The preceding addition plus the following addition is an integer, minus the difference between the following addition and the integer is equal to the sum.

Example: 1376 98 1474

Calculation: 1376 100 2

2. Find the sum of two two-digit numbers by reversing the position of the number.

The tens of digits of a number plus its single digits multiplied by 11 equals and.

Example: 47 74 121

Calculation: (4 7) x11 121

Subtraction Quick Calculation Tips:

1. Subtract the difference method.

The whole number of the subtraction is subtracted from the subtraction, plus the difference between the subtraction and the integer, which is equal to the difference.

Example: 321 98 223

Calculation: minus 100, add 2

2. Find the difference between two two-digit numbers in reverse the position of the number.

The decremented ten digits minus its single digit multiplied by 9 equals the difference.

Algorithms. Pen addition, to remember three points:

1. Align the same digits.

2. Add from single digits.

3. The single digit is full of 10 to 1 for the ten.

Written subtraction, to remember three points:

1. Align the same digits.

2. Subtract from the single digit.

3. If the single digit is not enough, subtract from the ten digits by 1, and add 10 to the single digit and then subtract it.

The quick calculation of addition and subtraction mainly uses the method of "rounding" to close to the whole method.

10. Whole hundred, whole thousand......The number is considered as a whole number.

10. Whole hundred, whole thousand......The number of calculations makes complex calculations simpler, thus increasing the speed of calculations.