We always have to solve math problems without the help of a calculator. Even if you are good at math, it is difficult to do mental arithmetic. If you want to solve problems with your brain alone, you need to use a completely different set of strategies and methods from what you learned in school. Fortunately, as long as you understand the basic principles and use mental arithmetic strategies, you can improve your ability in this area and solve complex calculation problems through your brain.

Method 1

Method 1 3:

Use mental arithmetic skills

1

Imagine this formula in your mind. If you want to solve math problems by mental calculation, you need to visualize the problems in your mind first. Imagine numbers and formulas in your mind. When solving some parts of the problem, let the new numbers that are being processed come to mind. Repeating numbers in your mind or mouth will also help you remember the more important numbers in the formula. 2

Add and subtract from left to right. When we learn addition and subtraction, we usually calculate from right to left, but this way will be more difficult in 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 constitute the high position in the answer, while the number on the right will be the low position. For example, to calculate 52+43, you can first calculate 5+4=9, and then calculate 2+3=5, making a total of 95.

If you want to calculate 93-22, first calculate 9-2=7, then calculate 3-2= 1, and the result is 7 1.

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

Calculation of odd and even zeros in addition and subtraction. When calculating the addition, we can find the parity zeros in the formula, and the calculation will become simpler after removing these zeros. For example, if you want to calculate 120-70, you can remove the parity zero, then the formula becomes 12-7=5, and then add the parity zero back, and the answer is 50.

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

four

When calculating multiplication, you can simplify the formula and add all zeros. When calculating multiplication, the formula can be simplified if there is a zero after the number. For example, to calculate 3000x50, you can simplify the formula to 3x5= 15, and then put all zeros after the product together to get 150000. Let's give another example. If you want to calculate 70x60, you can simplify it to 7x6=42, and then add zero to get 4200. five

When calculating the addition, round up first and then subtract the difference. When the number exceeds 100, you can round up first and then subtract the added number, thus simplifying the complicated addition problem. For example, if you want to calculate 596+380, you can add 4 to 596, and then the formula becomes 600+380=980, which makes mental arithmetic much easier. Then subtract 4 from the total to get 976, which is the sum of 596+380. Another example is 558+305. Round 558 to 560, and the formula becomes 560+305=865. Then subtract 2 from the sum 865 to get 863.

six

Simplify complex numbers when calculating multiplication. We don't always have to follow the numbers we see. Complex numbers or non-integer numbers will increase the difficulty of calculation. For example, calculating multiplication 12x36 can simplify numbers and make mental arithmetic easier. Change 12 to 10, and the formula becomes 10x36 equal to 360. Then calculate the mantissa that was not calculated just now, that is, 2 times 36, which equals 72. Finally, 360+72 gets 432. This makes the mental arithmetic of multi-digit multiplication easier.