How to learn mental arithmetic and how to calculate mental arithmetic

Multiplication and squared of 10-20.

Method: 1: Mantissa 2: The mantissa [full decimal place] of the multiplier is added by the multiplier 3:.

Example: 12*13=156

1: First phase the mantissa into 2*3=6

2: The mantissa of the multiplier plus the multiplier 12 + 3 = 15

3: Join the results = 156

square number arithmetic].

The first number is the same, and the sum of the mantissa is a two-digit method of 10.

Method: 1: Mantissa 2: Ten digits plus one 3: Multiply the beginning and the end.

Example: 54*56=3024

1: The mantissa is 4*6=24, which is directly written on the ten and single digits.

2: Ten digits plus one 5+1=6

3: Multiply the beginning and tail by 6*5=30

4: Join the results = 3024

The mantissa is 5 squared.

Method: Mantissa multiplication 2: 10 digits plus 1 3: multiply the first number.

Example: 25 squared.

1: Multiply the mantissa by 5*5=25, and write directly on the ten and unit digits.

2: Ten digits plus one 2 + 1 = 3, and then multiply the two numbers by 3 * 2 = 63: connect the results = 625

Nearly 100 squares of the number [nearly 1000 is OK].

Method: Subtract the number from 100, write the square of the difference on the single digit and the ten place, and subtract the difference from the number.

Example: 94.

2:6 squared = 36

3: Subtract the difference = 88 from this number, and write it in the hundred and thousand places.

4: Join the results = 8836

Any two squares of the book.

Method: 1: Square of the mantissa 2: Multiply the mantissa by two 3: Square the first number.

Example: 23 squared.

1: The square of the mantissa 3 = 9

2: Multiply the mantissa by two 2*3=6 6*2=12, written in the ten digits [full decimal place] 3: the square of the first number 2 squared = 4, plus the 1 in the ten digits, that is, 54: connect the results = 529

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Methods of mental arithmetic ability training:

1. Visualize the equation in your mind.

If you want to solve a math problem with mental arithmetic, you first need to visualize the problem in your mind. Imagine numbers and equations in your mind. When solving some part of the problem, let the new numbers that are being worked on come to mind.

2. Add and subtract from left to right.

When learning addition and subtraction, it is common to calculate from right to left, but this method is more difficult when doing mental arithmetic. When doing mental arithmetic, it is best to calculate the number on the left first, and then subtract or add the number on the right. The number on the left will form the higher digit in the answer, while the number on the right will be the lower digit.

For example, to calculate 52+43, you can first calculate 5+4=9 and then 2+3=5, resulting in a total of 95. If you want to calculate 93-22, first calculate 9-2=7, then 3-2=1, and the result is 71.

If there are numbers to be carried, add them to the first number. For example, when calculating 99+87, you can first calculate 9+8 to get 17, and then 9+7 to get 16. Because a carry of 1 is required, the first digit will become 18 and the final answer will be 186.

3. Calculation of zeros at the same position when adding or subtracting.

When calculating addition, you can find the zeros in the equation with the same position, and remove these zeros to make the calculation easier. For example, if you want to calculate 120-70, you can remove the zeros and change the equation to 12-7=5, then add the zeros back to get the answer 50.

Let's look at another example, if you want to calculate 300 + 200, you can remove the same zero, the equation becomes 3 + 2 = 5, and then add the zero back to get the answer 500.

Mental arithmetic does not rely on any tools, only uses the brain to perform arithmetic, relying on super memory and clear thinking ability;

Methods of mental arithmetic:

1. Algorithm: Written arithmetic training, answering questions should be written with a pen, and written arithmetic training is the main line of teaching; Do not use any physical calculation, regardless of horizontal, vertical, even addition and subtraction can be used, with a pen to do calculations is a golden key to start the smart express;

2. Knowing arithmetic: playing arithmetic, being able to write questions with a pen, being able to algorithmize, understanding arithmetic, and breaking through the calculation of numbers;

3. Practice speed: speed training, will use the pen to calculate the problem is insufficient, and the calculation must be completed within the specified time;

4. Enlightenment of wisdom: intellectual gymnastics, simply learning calculations, focusing on cultivating children's mathematical thinking ability, comprehensively stimulating the potential of the left and right brains, and developing the whole brain.

Ways to improve the speed of mental arithmetic:

1. Imagine the formula. When imagining numbers and formulas in your mind, and solving the part of the problem with lead, the new numbers that are being dealt with come to mind. Repeating numbers in a deep voice in the head and mouth helps to remember the more important numbers in the formula.

2. Addition and subtraction. When doing mental arithmetic, it is best to calculate from left to right.

3. The technical method of the same zero. If you want to calculate 200+400, you can remove the same zero, and the equation becomes 2+4=6, and then add the zero, and you can get the answer that the buried excitation is 600.

4. Simplify the calculation. If you want to calculate 30x60, you can simplify it to 3x6=18 and add zero to get 1800. The number can be simplified in this way by having zeros after it.

5. Addition rounding. When adding more than 100, you can round it up and then subtract the added number. Round 554 to 560 so that the equation becomes 560 + 207 = 767. Then subtract 6 from the sum of 767 to get 761.

6. Calculate multiplication. For example, in multiplication 13x24, you can simplify some numbers to make your mental arithmetic much easier. Turning 13 into 10 makes the equation 10x24 equal to 240.

7. Calculation of mantissa number. Then calculate the mantissa that was not calculated just now, that is, 3 times 24, which is equal to 72. In the end, 240+72 gets 312. This way the calculation will be faster.