Seven skills in the rapid calculation, we review it in front of you in order to help you calculate the exact accuracy and speed required, and of course the calculation of accurately and quickly stems from your knowledge of the four calculations and models reference tables (Tables multiplication from 1 to 9), which I have known in elementary And you should be able to train them all before you join the preparatory school.
You know Table 9 Of course:
There are models that give a quick way to review the multiplication table in 9 using your fingers. Your fingers are from 1 to 10 as shown in the image:
To multiply any number from 1 to 10 in 9 using the fingers, work as follows:
Look at the number that hits 9 and its position on the fingers and then the fingers to the left of the number is in the position of dozens and the number of fingers on the figure is in the status of the individual, for example 9 × 4, there are 3 fingers to the left of the number 4 and there are 6 fingers to the right of the number Vikon 9 × 4 = 36
Table multiplication using your fingers and your fingers numbers

2- Complications:
Complications are important and help us find a multiplication of any number by 2.
Try starting with 3 and multiply each time if you are able in two minutes
3; 6; 12; 24; 48; 96; 192; 384; 786; 1536; 3072 ....
You must multiply any large number starting from the end of the left of the number and multiply the first position, and then look at the status that follows. If the score is more than 4 we add one and if not, we do not add and continue to multiply all the numbers in the same way.
Example:
2 x 34793
The solution:
Weak 3 is 6, 4 the following figure is less than 5 we do not add one so we write 6 times 4. is 8, 7 is more than 5 so we add one and write 9 times 7 is 14, 9 is more than 5 so we add one and write 5 Because we added it in step kisses)
Weak 9 is 18, 3 is less than 5 so we do not add one and write 8 times 3 is 6 and write 6

In the same way, we can multiply any large number, writing the result from left to right

Do more than a dozen examples yourself Make sure you answer using the calculator
Complications result in finding the result of multiplication in 4 and 8 to multiply by 4, multiplying the multiplier by multiplication by 4 and multiplying the number three times by multiplying by 8
Do more than 10 examples yourself and make sure you answer using the calculator
Now put the base


4 × ... = 2 × (2 × ...)
8 × ... = (2 × (2 × (2 × ...)))
3- Classification:
The opposite of the weak is the adjustment.
Find half of the following numbers and test your answer using the calculator:
4682; 3484; 7528; 603638; 20304050
4 - beating in 5:
Multiply by 5 by the same multiplication in 10 (add zero to the multiplied number) and then half the output if the figure is even more than equal to the number and then add zero to clean.
If the figure is odd, just equal the number and add 5 to the stack. For example: 1369 × 5 is 6845 because half of 1369 is 684 and the number is 1369 individual so the result is 6845
5 - beating in 11:
We use the multiplicative multiplication property as follows:
11 = 10 + 1
To hit any number in 11 we do the following

11 × ... = 10 × ... + 1 × ...
Then write and combine the results
Example:
11 × 2643 = 10 × 2643 + 1 × 2643

There is another way:
You can check one of them on this page: beating in 11
6 - beating in 12:
We use the multiplicative multiplication property as follows:
12 = 2 + 10
To hit any number in 12 we do the following
12 × ... = 10 × ... + 2 × ...
Then write and combine the results
Example:
12 × 2473 = 10 × 2473 + 2 × 2473
= 24730 + 4946
7 - beating in 21:
Now apply the same https://www.pendsoft.com/2019/07/tor.htmlfor beating in 21, starting from left to right plus each position twice the position followed by the right.