How to calculate quickly in primary schools

How to do quick calculation in primary school? Many parents even started from kindergarten, starting with small math problems in their lives. On the premise of mastering the calculation rules and order, they can use fast calculation and clever calculation according to the characteristics of the topic itself. Let's see how to calculate quickly in primary schools.

How to calculate 1 quickly in primary schools: add up the numbers and round them off.

Add a few numbers. If several numbers can add up to a whole ten, you can change the position of the addend and add up several numbers.

For example: 14+5+6

= 14+6+5

=25

Quick calculation method: using the nature of subtraction to "round up"

Subtract several numbers from a number in succession. If the sum of subtraction can make up an integer, you can add the subtraction first and then subtract it. This kind of oral calculation is relatively simple.

For example: 50- 13-7

=50-( 13+7)

=50-20

=30

Fast algorithm: nearly ten, nearly a hundred, nearly a thousand numbers.

When calculating, we can regard the numbers close to whole ten, whole hundred and whole thousand as the numbers of whole ten, whole hundred and whole thousand.

Example:

1)497+ 136

497 can be approximately regarded as 500,

Original formula = (500-3)+ 136

=500+ 136-3

=633

2)760+ 102

Think of 102 as 100+2.

Original formula = 760+ 100+2.

=860+2

=862

Fast calculation method: supplementary method

Using "complement method", add 1 to each addend to form 20000, 2000, 200 and 20 for calculation.

For example:19999+1999+199+19.

Can be seen as:

(20000- 1)+(2000- 1)+(200- 1)+(20- 1)

=20000+2000+200+20-4

=22220-4

=222 16

How to do quick calculation in primary schools? There are three difficulties in primary school mathematics, and the formula foundation is difficult to memorize, especially for sixth-grade students who want to participate in junior high school. At this time, the teacher is conducting a comprehensive general review, and will review the mathematics knowledge points from the first grade to the sixth grade of primary school. It is not clear how many knowledge points need to be memorized in six math books. If you don't recite it, it means that you will lose points if you don't pass the exam. If you want to recite it, it means you must work harder.

Second, it is difficult to calculate. How many pupils' poor math performance is due to their poor computing ability? Please raise your hand. In particular, some eccentric children who love to get into the dead end will continue to do it until there is no way out when they encounter a calculation problem and don't work out the correct answer for three minutes. I usually agree with this practice, and so do the exams. Sorry, there is probably no time to do the following application questions.

The idea of solving three difficult problems needs the support of children's logical thinking, but the teacher is most worried about the best expressive force of students. Because today's parents attach great importance to children's thinking training, many parents even start to train their children's logic from math minor problems, such as brain teasers, so many children's problem-solving ability is actually the best.

But among the three, the most difficult is the ability to calculate, because most children now have a common problem: carelessness. Calculation problems are the easiest to make careless mistakes. Some seemingly simple mathematical calculation problems actually contain "traps" and will be deducted if they are not careful. I have seen junior high school children before. Originally, the previous steps were all right, but the last step was the wrong number and the wrong answer. Although not all points will be deducted, if you get into a prestigious school, you will still be admitted by one or two points. It's a pity to think about it.

Let children form the good habit of doing math and calculation problems seriously. Some parents say that their children are careful, but the calculation speed is also dragging their feet. How can we be careful and ensure the speed and accuracy of solving problems? Just asked the point, I happen to have a quick calculation method here. What the children have to do next is to practice them carefully during the winter vacation until they are familiar with them. I'm sure I can do well in the opening exam next semester!

How to calculate 3 quickly in primary school? 1. Multiplication and rounding

Ideological core: First, combine several multipliers that can add up to whole ten, whole hundred and whole thousand, and then multiply them with the previous numbers to make the operation simple.

Theoretical basis: multiplication exchange rate: a× b = b× a.

Multiplication combination rate: (a×b) ×c=a×(b×c)

Multiplication distribution rate: (a+b) × c = a× c+b× c.

Law of product invariance: a×b=(a×c) ×(b÷c)=(a÷c) ×(b×c)

Second, the nature of the mixed operation of multiplication and division

(1) quotient invariance: divisor and divisor multiply (or divide) the same non-zero number, and their quotient remains unchanged.

(2) In division, the positions of divisors are interchangeable and the quotient remains unchanged.

(3) In the mixed operation of multiplication and division, the multiplicand, multiplier or divisor can exchange positions with the operation symbol (that is, move with the symbol).

(4) Rules for removing or adding brackets in mixed operation of multiplication and division.

Remove the brackets: ① When the "×" comes before the brackets, the symbol of multiplication and division in the brackets will remain unchanged after the brackets are removed.

(2) when there is a \ in front of the bracket, after removing the bracket, the × in the bracket becomes \ \, and \ becomes ×.

When brackets are added: when brackets are added, the original symbol is unchanged when an "×" is added before brackets; When there is a \ \ before the bracket, the original symbol \ \ becomes \ \, and \ \ becomes \ \.

The product of two numbers divided by the product of two numbers can be divided separately and then multiplied.

All the above three properties can be extended to the case of multiple numbers.

Third, the fast calculation skills of multiplication

1, head to tail:

Applicable conditions: two digits multiplied by two digits, the first digit is the same, and the mantissa adds up to ten.

Practical examples:

53×57=302 1

48×42=20 16

Operation description: Head× (head+1) is the head, and tail× tail is the last two digits.

2. Multiply two digits by 1 1:

Practical examples:

25× 1 1=275