Three, the right hand refers to practice the formula, two tigers contend, in a few words, the four seas are home, the grain is abundant, the six animals are prosperous, the Eight Immortals cross the sea, and the nine Niu Yi hairs are urgent. Keep one word, two dragons play with pearls, three pillars stand on each other, besieged on all sides, rich in grain, anxious about six gods, exquisite in all directions, and nine Niu Yi are exhausted. (Note: When reading "urgent" or "perfect", make a fist in your right hand and put "1" in your left hand, indicating carry. )
Fourth, the left hand points out the practice formulas ten, twenty, thirty and forty; Fifty, sixty, seventy, eighty, ninety, one hundred. (Note: When I read "100", I advise you to be full of happiness, high-five, and then put your fist on your chest. )
Five, two-hand counting exercises 15, 23, 46, 99, 58, 73, 6 1 ... (Note: Choose the counting size according to the cognitive level of children of all ages. )
1 section adds subtraction.
Method: In an addition formula, if the addend or one of the addends is close to integer ten, integer hundred, integer thousand, etc. , are integers added, and then subtract the difference (that is, complement), which is very convenient to calculate. Fast calculation of children's addition and subtraction fingers
Formula: Add the first addend to the whole ten, whole hundred and whole thousand of the second addend, and then subtract the difference between the second addend and the whole ten, whole hundred and whole thousand, which is equal to sum.
Section 2: Find the sum of only two digits in the position transformation of two digits.
Method: In a two-digit addition, if the ten digits of the addend and the single digits of the addend are the same, then the sum of the ten digits and the single digits of the addend multiplied by 1 1 is the sum of this addition.
Mouth formula: (beginning and end) × 1 1= and children's addition and subtraction finger quick calculation.
For example: 5885 = (58) ×11=143.
How to carry and abdicate children's fingers quickly? I used to be a teacher of counting fingers many years ago, but now I don't teach this method. If you want to learn to advance and retreat, you must learn complement well. If you don't learn complements, you are in a dilemma. For example: 4+8=. (The right hand represents a unit, and the left and right represent ten digits.) If the right hand reaches out 4 first, adding 8 fingers is not enough, then subtract 8' s complement 2, and then carry 10 with the left hand, that is, extending one finger with the left hand is equal to 12.
9+6= the right hand extends 9, and adding 6 cannot be directly expressed by the right hand, so the complement 4 of 6 should be subtracted first, and then the left hand carry 10 (that is, extending a finger) is equal to 15. The finger calculation method is simple and easy to learn, and the calculation accuracy is quite high. But the disadvantage is that children will feel dependent. Although it is fast, the speed of the answer sheet is not high. Time is wasted in practicing by hand, then writing with a pen, putting down the pen and practicing by hand, then writing with a pen and counting by hand. . . But the biggest disadvantage is that it is easy to confuse children's cognition of logarithm. In traditional teaching, thumb means 1. But in finger calculation, it means 5. Thumb plus index finger means 2, but in finger calculation, it means 6. We have ten fingers, and when we extend our hands, it is 10, but in finger calculation, it is 99. There are too many examples. When I just graduated from college, I didn't know much about these things and spent a lot of money on training. It is beneficial for kindergarten teachers to teach their fingers quickly and see their grades quickly. Kindergarten does not require time to do problems! But the same method is not the case in primary schools. Ha ha! If it is really good for children, you can go to Baidu to look at the information of quick mental arithmetic and pen quick calculation. Personally, I think this fast calculation method is acceptable. Simple advice. I wish your child good grades. Happy new year!
How to calculate the solution of 38+5 addition;
38+5
=38+(2+3)
=38+2+3
=(38+2)+3
=40+3
=43
How to add 34 to 79 in finger quick calculation? 79+34 = (70+30)+(9+4) =100+13 =13 ... Ten digits, plus ten digits, plus one digit.
Fast finger calculation: 70+30...7+3 = 10 ... Actually, it is 100...9+4 = 13 ... The total number is:1kloc-0/3.
How to teach carry addition should pay attention to two points: first, the number of digits should be aligned, that is, the end should be aligned; Two, full ten into one, full ten into one.
Use a few examples to demonstrate, give appropriate guidance in the initial exercise, encourage you to do well and correct your mistakes.
How to do carry addition? A mathematical operation, an addition. When two numbers are added, if the result of one bit is greater than or equal to 10, you need to count 1 to the next bit, which is the carry. For example:
48
+ 56
————
= 104
8+6 = 14 & gt； 10 rises by one place (ten places) to 1.
4+5 plus rounded 1, that is, 4+5+ 1= 10 also needs to be rounded up by one hundred digits to 1.
When there is carry addition in the operation, it is called "carry addition".
How to calculate the finger speed algorithm from 7 to 4? The finger speed algorithm 7 minus 4 is calculated as follows: Mr. Wang gives 7 fingers, then bends 4 fingers, and the remaining 7-4=3 fingers are vertical.
My friend, please adopt the correct answer in time, which may help you next time. If you use the correct answer, you can also get wealth value. Thank you.