What are the skills of continuous subtraction for elementary school students

The continuous subtraction method is usually calculated in order from left to right, but in the actual calculation, a reasonable calculation method can be selected according to the characteristics of the number of questions, so as to make the calculation easier. There are two main simple algorithms for continuous subtraction.

1. Swap the positions of the two minus numbers and then subtract.

Example 1: 1851 132 251 = 851 251 132 = 600 132 = 468

Example 2: 6852 235 6352 = 6852 6352 235 = 500 235 = 265

2. Subtract the sum of several minuses from the subtracted number.

Example 3: 4791 1386 614 = 4791 (1386 614) = 4791 2000 =2791

Example 4: 6524 312 212 =6524 (312 212) =6524 524 =6000

In fact, calculating the sum of two numbers minus one number can also be reversed by subtracting the two numbers in turn using the arithmetic properties of subtraction, so as to make the calculation easier.

Example 5: 3082 (1082 519) = 3082 1082 519 = 2000 519 = 1481

Example 6: 762 (117 362) = 762 362 117 =400 117 =283

You can add the subtractions first, and then use the subtracted numbers to add the subtractions.

The most important thing is to be careful and serious.

Seriously, carefully, memorize the subtraction formula.

Grade 1 Mathematics Consecutive Subtraction Method, Carry Addition Calculation Method.

Whether it is two digits plus one digit, two digits plus two digits are applicable, the most basic principle of branches such as mu is the addition principle within 20, and the quick calculation formula for carry addition within 20 is: several + 9, advance 1 minus 1; a few +8, 1 minus 2; a few + 7, into 1 minus 3; a few +6, 1 minus 4; a few + 5, into 1 minus 5; a few + 4, into 1 minus 6; a few + 3, into 1 minus 7; a few + 2, 1 minus 8; A few + 1, 1 minus 9.

The short-answer calculation method of abdication subtraction. The quick calculation of abdication and subtraction is: a few -9, ten + 1 back;Few-8, 10+2;Few-7, 10+3;Few-6, 10+4;Few-5, ten + 5;Few-4, 10 + 6;Few-3, 10+7;Few-2, 10+8;A few -1, ten + 9.

In subtraction, the subtraction and the subtraction cannot be exchanged, so in subtraction, first observe the two single digits, when the subtraction is larger than the single digit of the subtracted number, calculate according to the subtraction formula, that is, you can quickly calculate the answer.

Subtraction:

Subtraction is a basic arithmetic operation, and the operation of subtracting another quantity from one quantity is called subtraction, and the result becomes a difference. The sum of two additions is known to be the sum of one of the additions, and the operation of finding the other addition is called subtraction. The symbol for subtraction is "-" read as a minus sign.

Used to calculate the reduction!

Subtraction doesn't have to be hard calculations, but it can also be simple calculations. This method is suitable for children in preschool and first grade. For example:

24-8=16 can be thought of like this: borrow 14-8, first use 10-8=2, then use 2+4=6, the difference must be 6, and ten digits are simple. That is to say, after borrowing a place, remove the number of the single digit and subtract it first, and then use the subtracted number to add the number of the subtracted single digit, and it is not difficult to have ten digits.

The arithmetic techniques for adding and subtracting are as follows:

Tools Raw materials.

Vertical operation algorithm.

Integer method. Take 25+16+18 as an example, and calculate the two ways of the vertical algorithm.

1. The first is to add the first two numbers to the first two numbers, and then use the number to add the third number.

Step 1 Use the vertical calculation method to calculate: 25+16=41

Step 2 Continue to calculate using the vertical calculation method: 41+18=59

The arithmetic skills of even arguing and subtracting.

2. The second is to add the three numbers together.

Directly list the three in vertical red, adding single digits and single digits, and adding tens and tens respectively. If the single digit is increased by 10 or equal to 10, it needs to be advanced to 10 digits; If the number of tens is increased by or equal to 100, it needs to be further to the hundreds.

Calculation skills of adding and subtracting.

Take 59-18-16 as an example, and calculate the two ways of the vertical algorithm.

1. The first is to subtract the second number from the first number, and then use the number to subtract the third number.

Step 1 Use the vertical calculation method to calculate: 59-18=41

Step 2 Continue to calculate the vertical method: 41-16=25

Calculation skills of adding and subtracting.

2. The second way is to use the first number and subtract the first number directly.

Second, the third number.

Directly list the three in vertical red, subtracting the single digit from the single digit, and subtracting the ten digit from the ten. If the first single digit is not enough to subtract, you need to borrow one from the ten digits.

Calculation skills of adding and subtracting.

Rounding method. 1. In addition to the vertical algorithm, you can also use the integer method, which is to add 10 to get 10, or subtract to get 0 to operate first, and then use the remaining numbers to add or subtract.

For example: 22+29+11, you can calculate 29+11=40 first, and then 22+40=66;

55-26-16, you can calculate 26-16 = 10 first, and then 55-10 = 45.

Calculation skills of adding and subtracting.

Precautions

Proficient memorization of calculations within 20 is conducive to continuous addition and subtraction calculations.

The continuous subtraction method is usually calculated in order from left to right, however, in the actual calculation, sometimes according to the characteristics of the number of pants in the question, a reasonable calculation method can be selected, so that the calculation is simple, and the continuous subtraction method mainly has the following three simple algorithms.

Skills: 1. Swap the positions of the two minuses and then subtract;

2. Subtract the sum of several subtractions from the subtracted number;

3. Calculate the sum of two numbers minus one number, or you can use the operation properties of the closed subtraction method to subtract these two numbers in turn, so as to make the calculation simple.

Continuous subtraction is a number subtracting two numbers in a row, which can be equal to the sum of the two numbers minus this number, and the number remains the same. Subtraction is one of the four operations, the operation of subtracting another number from one number is called subtraction; It is known that the sum of two additions and one of the additions rolls friends, and the operation of finding the other addition is called subtraction. The symbol for subtraction is "-" read as a minus sign.

Subtraction follows several important patterns. It is anti-commutative, meaning that changing the order changes the symbol of the answer. It is not binding, that is, when a minus exceeds two numbers, the order of subtraction is important.

Subtracting 0 does not change a number. Subtraction also follows the rules of relatability related to operations such as addition and multiplication. All of these rules can be proven, starting with the subtraction of integers and generalized by real numbers and other things.

General binary operations that continue these patterns are learned in abstract algebra.

The continuous subtraction method is: a number subtracts two numbers in a row, which can be equal to the sum of the two numbers minus this number, and the number remains the same.

For example: a-b-c=a-(b+c).

Trick 1 friend with infiltration: Round. Integer is to first add the single digits to make up the number of tens, connect the line to find the result, and finally calculate all the results.

Tip 2: Split and complement. If you encounter a problem that cannot be rounded, you can split one of the numbers into several numbers (the sum of several numbers is equal to the number before the split), and then round the split number with other numbers.

Tip 3: Change the order of operations. In the process of calculation, you can put together the same or smaller numbers that can be rounded together as needed, and then calculate the resulting results.

First, such as complements and the like, but these elementary school students are estimated to be able to touch the door, and it is definitely useful to read some professional books, but they still need a lot of practice.

Second, in the process of calculating the addition and subtraction, you can round up the numbers, and then add or subtract the numbers that are overcounted or undercounted.

For example: 48 21 97 104 can be regarded as 50 20 100 100 2 1 3 4, in the past, the mouth twist account or a clear mouth is calculated in this way, as long as you are proficient, or add hand calculation, the effect is better.

Compared to multiplication and division, addition and subtraction are not very skillful, and you want to get the strongest brain.

At that speed, you can only practice more.

1. Try to put the same single digit number together to calculate. For example: 36+12+26+22=?

We can follow (36+26)+(12+22)=? To calculate, 3 + 2 = 5 digits on the ten digits in the first parenthesis = 6 + 6 = 12 and then 50 + 12 = 622, try to round up. For example:

23+64+37=？At this time, first move the position of the additive, and it becomes 23+37+64=? The addition of 23 and 37 produces an integer for later calculations.

23 + 37 = 60, 60 + 64 = 124 commonly used numbers when rounding: 1 + 9 2 + 8 3 + 7 4 + 6 5 + 53, integers are calculated together (addition and subtraction are applicable) for example: 20 + 13 + 30 = 20 + 30 + 13 = 50 + 13 = 6360-17-40 = 60-40-17 = 20-17 = 34, the same single digit is put together (even subtracted) This is not the same as even adding, When the single digit is the same, the subtraction must be equal to zero, so there is no need to think about counting the ten digits directly, such as: