The knowledge obtained in the lessons of algebra and geometry in life people use extremely rarely. The most valuable and necessary skill associated with mathematics is the ability to quickly count in the mind, so it is worthwhile to figure out how to learn it. In ordinary life, this allows you to quickly calculate the change, calculate the time, etc.
It is best to develop abilities from the very childhood, when the brain learns information much faster. There are several effective techniques that many people use.
How to learn to count very quickly in the mind?
To achieve good results, it is necessary to conduct training regularly. After achieving certain goals, it is worth complicating the task. Of great importance are the abilities of a person, that is, the ability to keep several things in memory and concentrate attention. The greatest success can be achieved by people with a mathematical mindset. To quickly learn to count, you need to know the multiplication table well.
The most popular methods of counting:
- We'll figure out how to quickly calculate two-digit numbers in the mind, if you want to multiply by 11. To understand the technique, let's look at one example: 13 multiply by 11. The problem is that between numbers 1 and 3 you need to insert their sum, that is 4. As a result, it turns out that 13x11 = 143. When the sum of the digits gives a two-digit number, for example, if you multiply 69 by 69, then 6 + 9 = 15, then you only need to insert the second digit, that is, 5, and add 1 to the first digit of the multiplier. As a result, you get 69x11 = 759. There is another way to multiply the number by 11. To begin with, multiply by 10, and then add the original number to it. For example, 14x11 = 14x10 + 14 = 154.
- Another way to quickly count large numbers in the mind works for multiplication by 5. This rule is suitable for any number that needs to be divided by 2 for the beginning. If the result is an integer, you must assign zero at the end. For example, to find out how much 504 will be multiplied by 5. To do this, 504/2 = 252 and attributed at the end of 0. As a result, we get 504x5 = 2520. If, when dividing a number, you do not get an integer, you just need to remove the comma. For example, to find out how many times 173 is multiplied by 5, you need 173/2 = 86.5, and after that just remove the comma, and it turns out that 173x5 = 865.
- We learn how to quickly calculate in mind two-digit numbers, by addition. First you need to add tens, and then, units. To get the final result, you must add the first two results. For example, we'll figure out how much will be 13 + 78. The first action: 10 + 70 = 80, and the second: 3 + 8 = 11. The final result will be as follows: 80 + 11 = 91. This method can be used when one has to subtract another from one number.
Another urgent topic is how quickly to calculate percentages in the mind. Again, for a better understanding, consider an example of how to find 15% of a number. First, determine 10%, that is, divide by 10 and add half of the result -5%. Find 15% of the 460:
There is another method, how to calculate interest. For example, if you need to determine how much will be 6% of 400. To begin with, it is necessary to find out 6% of 100 and this will be 6. To find 6% of 400, you need 6x4 = 24.
If you need to find 6% of 50, then you should use this algorithm: 6% of 100 is 6, and for 50, this is half, that is 6/2 = 3. As a result, it turns out that 6% of 50 is 3.
If the number from which you want to find a percentage less than 100, you just have to move the comma to the left. For example, to find 6% of 35. First, find 6% of 350 and it will be 21. The value of the same 6% for 35, is 2.1.