For example:
1、40÷2=
40 can be seen as 4 times 10. What about 40? Can I count 2 as 4 first? 2. Painting
40÷2=4? 2? 10=20
2、400? 2=
400 can be seen as 4 times 100. What about 400? Can I count 2 as 4 first? 2. Painting
400÷2=4? 2? 100=200
3、440? 2=
440 can be seen as 4 times 100 plus 4 times 10, so 440? Can I count 2 as 4 first? 2. Painting
440÷2=(400+40)? 2=400? 2+40? 2=220
Baidu baike
Oral arithmetic and quick mental arithmetic are different from abacus mental arithmetic and palm mental arithmetic. The fast mental arithmetic invented by Niu Hongwei, a teacher in Xi 'an, mainly trains children to do addition, subtraction, multiplication and division quickly through certain rules in textbooks. "Quick mental arithmetic" helps to improve the order, logic and sensitivity of children's thinking and behavior, and trains children's eyes, hands and brains to react quickly. The calculation method is consistent with that of primary and secondary school mathematics, so it is very popular with children and parents. Oral arithmetic and quick mental arithmetic: a teaching mode that is truly synchronized with primary school mathematics textbooks;
1: Knowledgeable algorithm
Written calculation training, China's current education system is exam-oriented education, and the standard for testing students is the test report card. Then the students' main tasks are to take exams, answer questions and write with a pen. Writing arithmetic training is the main line of teaching. Consistent with the mathematical calculation method in primary schools, it does not use any physical calculation, and can be used freely horizontally and vertically, even adding and subtracting. Computing with a pen is the golden key to opening an intelligent express train.
Step 2 be clear and reasonable
Try to find out. Children should not only learn arithmetic, but also know it. Let children understand the calculation principle and break through the calculation of numbers in spelling. The child completes the calculation on the basis of understanding.
Step 3 practice speed
Speed training, it's not enough just to use pen to calculate problems. There is definitely a time limit for primary school oral arithmetic. It takes time to tell whether it is up to standard, that is, it is not enough to calculate problems, mainly to speed up.
4. Enlightenment wisdom
Intellectual gymnastics, not simply learning and calculating, focuses on cultivating children's mathematical thinking ability, fully stimulating the potential of the left and right brains and developing the whole brain. After rapid mental arithmetic training, preschool children can deeply understand the essence of mathematics (including), the meaning of numbers (cardinal number, ordinal number, including), the operation mechanism of numbers (addition and subtraction of numbers with the same number) and the way of mathematical logic operation, so that children can master the method of dealing with complex information decomposition and develop divergent thinking and reverse thinking. The child's brain works fast.
(Source: Baidu Encyclopedia: Oral)