Honesty is one of the four basic operations. Knowing the sum of two addends and one of them, we can find the other addend.

The operation is called sincere method. The symbol of subtraction is "_", which is pronounced as negative sign.

Subtraction is a mathematical operation that represents the operation of removing an object from a collection. Its symbol is the minus sign (-). For example, on the right.

There are 5-2 apples and 5 apples in the picture. Take away 2 apples and there are 3 apples left. So 5-2= 3. Subtraction representation

Use different objects (including negative numbers, fractions, irrational numbers, vectors, decimals, functions and matrices) to remove or reduce physics and abstraction.

The number of.

Subtraction follows several important patterns. It is anti-commutative, which means that changing the order will change the sign of the answer. It has no knot.

Consistency, that is, when a subtraction exceeds two numbers, the order of subtraction is very important. Subtracting 0 will not change 1.

Numbers.

Subtraction also follows predictable rules related to addition and multiplication. All these rules can be proved from integers.

Subtraction begins and is summed up with real numbers and other things. Continue the general binary operation of these patterns in abstract algebra.

Learn from it.

The relationship between addition and subtraction;

The operation of combining two addends into one number is called addition. Given the sum of two addends and one of them, the operation of finding the other addend is called subtraction. Subtraction is the inverse of addition. Using the addition and subtraction relation, we can check whether the result of the addition and subtraction formula is correct, and we can also find out the unknowns in the addition and subtraction formula.

Subtraction is the inverse of addition. Appendix+Appendix = sum, one addend = sum-another addend. In other words, the sum in addition is equivalent to the minuend in subtraction, and the sum and difference of the minuend are equivalent to the addend in addition. Addition and subtraction are reciprocal operations: subtraction can be written in the form of addition, such as a-b=a+(-b), and addition can also be written in the form of subtraction, such as a+b=a-(-b).

Introduction to addition:

Addition is one of the four basic operations, which refers to the calculation of combining two or more numbers and quantities into one number and quantity. The symbol of addition is the plus sign "+". Connect items with a plus sign when adding. They are interchangeable, that is to say, the order is not important and they are interrelated.

This means that when more than two numbers are added, the order of addition is not important. Repeatedly adding 1 is the same as counting; Adding 0 will not change the result. Addition also follows related operations such as subtraction and multiplication. Addition is one of the simplest digital tasks. The most basic addition: 1+ 1 five-month-old babies and even other animal species can be counted.

From experience, the sense of number is alive;

Mathematics is a science that people qualitatively grasp and quantitatively describe the objective world. It originates from life and ultimately serves life. Mathematics teaching should be closely linked with students' real life, and only by building abstract mathematics on students' vivid and rich life background.

In fact, it can stimulate students' interest in learning mathematics and generate motivation to learn mathematics well.

The sense of number needs to be cultivated slowly, so that students can actively perceive and explore, and let them realize that mathematics is in the surrounding life, and life can be solved with mathematical knowledge.

Mathematical phenomena and problems make students feel the fun of learning mathematics. In this way, students can not only learn knowledge, but also cultivate their ability and sense of numbers.

For example, when teaching "small shops", I first asked the children to make some handmade products at home as commodities and bring them.

In math class, in this way, math class has become a "small shop". Then let the children take turns to be salespeople and customers.

Carry out commercial activities. Before the activity, let the children prepare learning tools for RMB samples of various denominations.

Yuan money depends on who buys more things and buys better things. After buying it, let the children evaluate each other. Complete the activity.

After collective discussion, let them talk about what they bought, how much each item cost, how much they spent and how to calculate it.

Through this activity, the children learned more about RMB and mastered the exchange of RMB better. he

Students also deeply feel the close connection between mathematics knowledge and life, and feel that mathematics is in the life around us, so as to perceive the sense of numbers.

Hands-on operation, number sense concretization:

Piaget once said: "Children's thinking begins with action. If we cut off the connection between action and thinking, thinking will not develop; " The flower of wisdom is in your hand. "Hands-on activities can show students' learning process and make students' experience continuous.

Change and upgrade. Paying attention to hands-on mathematics classroom will become a paradise for students to explore and a cradle of innovation. Therefore, the cultivation and development of number sense can not be separated from hands-on operation.

For example, when teaching "knowing numbers within 100", I asked the children to take out 35 math sticks. So, I watched how the children accepted it.