how to do Faster Mathmatical Calculations --Mentionaly---Do Maths Calculations Without Pen and Paper

.Let’s start with the first sutra, by one more than the one before.
This sutra helps you figure out how to square numbers that ends with a 5; like 452, 252, 552 etc.
Okey, let’s look at 452. Start by squaring 52=25. Then you take the 4 and multiply by one more, 5, and you get 20.
So, 452=2025
252= 2*3 and 25=625
552=3025
Easy right?
Okey let’s move one to the next sutra, all from 9 and the last from 10.
This sutra is used for subtractions. It works for subtractions when you subtrack from numbers starting with a 1 followed by zeros, like 100, 1 000, 10 000 etc.
100-69= (9-6) and (10-9) = 31
So, all the numbers before the last number you subtrack from 9 and the last number from 10.
1 000-594= (9-5) and (9-9) and (10-4) = 406
10 000-6 437= (9-6), (9-4), (9-3), (10-7) = 3 563
10 000-489 = 10 000-0 489 = (9-0), (9-4), (9-8), (10-9) = 9 511
How hard was that?
Vertically and Crosswise is mainly used for multiplication and fractions.
Okey, let’s start with an example, 9*6.
9 1 = (10)
*
6 4 = (10)
——
5 4
You start by subtracking from 10 to get the right digits. Then you subtract crosswise to get the first figure, so either you go with (6-1) or (9-4), wich is 5. To get the last digit you just multiply 4 with 1 and gets 4.
7*8 = ?
7 3 = (10)
*
8 2 = (10)
——
5 6
(8-3) or (7-2) = 5
(3*2) = 6
Vertically and crosswise can also be used for numbers close to 100.
80*96 = ?
80 + 20 = (100)
*
96 + 4 = (100)
——-
76 80
(80-4) and (20*4)
Multiplying with numbers just over 100.
103 * 105 = (103+5) and (5*3) = 10815
101 * 123 = (101+23) and (1*23) = 12423
Let’s look at another example when you can use vertically and crosswise, fractions.
2/3 + 1/6
Here you multiply crosswise, 2*6 and 3*1 and then add them together, and then you multiply the lowest figures vertically, 3*6. So the result is (12+3)/18 = 15/18
5/7 + 3/4
((5*4) + (7*3))/(7*4) = (20+21)/28 = 41/28
You can use vertically and crosswise on all multiplications:
23*56 = ?
23
*
56
————
(2*5) and (6*2)+(5*3) and (6*3) = 10; 27; 18 = 1288
You add the 2 from 27 to the 10 and you add the 1 from 18 to the 7. Easy as hell.
56*78 = ?
56
*
78
————–
(5*7) and (5*8)+(7*6) and (8*6) = 35; 82; 48 = 4368
Multiplying by 11.
This is really a piece of cake. You just add the number together in the middle, like this:
45 * 11 = 4, the first digit. 4+5=9. 5, the last digit. = 495
79 * 11 = 869
234 * 11 = 2574
Dividing by 9.
This is not exactly the correct answers as you can see but very close. Can be used for assumptions.
34/9 = 3,7
3*9=27 and 4*9=36, so the only possible figure is 3. And the 7 you simply get from adding 3 and 4 together.
46/9 = 4 + 10 = 5 (you move over the 1 from 10 as I have showed before)
139/9 = 1 + 4 + 13 = 15,3 (the 1 comes from the first figure, the 4 from adding 1 and 3, 13 from adding 1,3 and 9.