criss-cross multiplication.pdf
DESCRIPTION
Criss-Cross Multiplication.pdfTRANSCRIPT
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This is one of the fastest techniques of multiplication…
Helps you get the answer of any multiplication problem in just one line !
We will begin with multiplication of two-digit numbers
![Page 3: Criss-Cross Multiplication.pdf](https://reader035.vdocuments.us/reader035/viewer/2022081801/55cf9b0c550346d033a4889d/html5/thumbnails/3.jpg)
We will use the 3 steps that are given below:
A) * *
* *
B) * *
* *
C) * *
* *
![Page 4: Criss-Cross Multiplication.pdf](https://reader035.vdocuments.us/reader035/viewer/2022081801/55cf9b0c550346d033a4889d/html5/thumbnails/4.jpg)
Let us suppose we want to multiply:
2 3
x 1 2
![Page 5: Criss-Cross Multiplication.pdf](https://reader035.vdocuments.us/reader035/viewer/2022081801/55cf9b0c550346d033a4889d/html5/thumbnails/5.jpg)
We follow step (A) as seen before:
A) * *
* *
2 3
X 1 26
We get the answer as (3 x 2) equals 6.
![Page 6: Criss-Cross Multiplication.pdf](https://reader035.vdocuments.us/reader035/viewer/2022081801/55cf9b0c550346d033a4889d/html5/thumbnails/6.jpg)
We follow step (B) as seen before:
B) * *
* *
2 3
X 1 26
We cross-multiply and add. (2 x 2) + (1 x 3) is 7.
7
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We follow step (C) as seen before:
A) * *
* *
2 3
X 1 26
We get the answer as (2 x 1) equals 2.
72
The final answer is 276
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Another example…
Let us suppose we want to multiply:
3 4
x 1 1
![Page 9: Criss-Cross Multiplication.pdf](https://reader035.vdocuments.us/reader035/viewer/2022081801/55cf9b0c550346d033a4889d/html5/thumbnails/9.jpg)
We follow step (A) as seen before:
A) * *
* *
3 4
X 1 14
We get the answer as (4 x 1) equals 4.
![Page 10: Criss-Cross Multiplication.pdf](https://reader035.vdocuments.us/reader035/viewer/2022081801/55cf9b0c550346d033a4889d/html5/thumbnails/10.jpg)
We follow step (B) as seen before:
B) * *
* *
3 4
X 1 14
We cross-multiply and add. (3 x 1) + (4 x 1) is 7.
7
![Page 11: Criss-Cross Multiplication.pdf](https://reader035.vdocuments.us/reader035/viewer/2022081801/55cf9b0c550346d033a4889d/html5/thumbnails/11.jpg)
We follow step (C) as seen before:
A) * *
* *
3 4
X 1 14
We get the answer as (3 x 1) equals 3.
73
The final answer is 374
![Page 12: Criss-Cross Multiplication.pdf](https://reader035.vdocuments.us/reader035/viewer/2022081801/55cf9b0c550346d033a4889d/html5/thumbnails/12.jpg)
More Examples:
3 2 3 1 1 4
x 2 1 x 1 2 x 2 16 : 3+4 : 2 3 : 6+1 : 2 2 : 8 + 1 : 4
6 7 2 3 7 2 2 9 4
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Two-digit Multiplication With Carry-over
Example:
4 4
x 2 2
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Step (A) will be :
A) * *
* *
4 4
X 2 28
We get the answer as (4 x 2) equals 8.
![Page 15: Criss-Cross Multiplication.pdf](https://reader035.vdocuments.us/reader035/viewer/2022081801/55cf9b0c550346d033a4889d/html5/thumbnails/15.jpg)
Step (B) will be:
B) * *
* *
4 4
X 2 28
We cross-multiply and add. (4 x 2) + (4 x 2) is 16. We write 6 and carry-over 1.
6
1
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Step (C) will be:
A) * *
* *
4 4
X 2 28
We multiply (4 x 2) and get 8. We add the 1 carried over and get the final answer as 9
69
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3-digit MultiplicationWe will use the 5 steps that are given below:a) * * *
* * *
b) * * *
* * *
c) * * *
* * *
d) * * *
* * *
e) * * *
* * *
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Step (A) will be :
A) * * *
* * *
3 0 2
X 1 2 12
We get the answer as (2 x 1) equals 2.
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Step (B) will be :
A) * * *
* * *
3 0 2
X 1 2 12
We get the answer as (0 x 1) + (2 x 2) equals 4.
4
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Step (C) will be :
A) * * *
* * *
3 0 2
X 1 2 12
We get the answer as (3 x 1) + (0 x 2) + (2 x 1) equals 5.
45
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Step (D) will be :
A) * * *
* * *
3 0 2
X 1 2 12
We get the answer as (3 x 2) + (1 x 0) equals 6.
456
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Step (E) will be :
A) * * *
* * *
3 0 2
X 1 2 12
We get the answer as (3 x 1) equals 3.
4563
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Three-digit Multiplication With Carry-over
5 0 2
x 1 6 1
Example:
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Step (A) will be :
A) * * *
* * *
5 0 2
X 1 6 12
We get the answer as (2 x 1) equals 2.
![Page 25: Criss-Cross Multiplication.pdf](https://reader035.vdocuments.us/reader035/viewer/2022081801/55cf9b0c550346d033a4889d/html5/thumbnails/25.jpg)
Step (B) will be :
A) * * *
* * *
5 0 2
X 1 6 12
We get the answer as (0 x 1) + (6 x 2) equals 12. We write 2 and carry-over 1.
2
1
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Step (C) will be :
A) * * *
* * *
5 0 2
X 1 6 12
We get the answer as (5 x 1) + (0 x 6) + (2 x 1) equals 7…(plus 1 carried over) equals 8
28
1
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Step (D) will be :
A) * * *
* * *
5 0 2
X 1 6 12
We get the answer as (6 x 5) + (1 x 0) equals 30. We write 0 and carry-over 3.
280
3
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Step (E) will be :
A) * * *
* * *
5 0 2
X 1 6 12
We get the answer as (5 x 1) equals 5. We add to it the 3 carried over. The final answer is 8.
2808
3
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More Examples:
3 4 2 3 6 1 7 1 4
x 2 0 1 x 1 4 2 x 9 3 5
68742 51262 667590
![Page 30: Criss-Cross Multiplication.pdf](https://reader035.vdocuments.us/reader035/viewer/2022081801/55cf9b0c550346d033a4889d/html5/thumbnails/30.jpg)
Let us have a look at the steps used in multiplication of four digit numbers…
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4-digit MultiplicationWe will use the 7 steps that are given below:a) * * * *
* * * *
b) * * * *
* * * *
c) * * * *
* * * *
d) * * * *
* * * *
e) * * * *
* * * *
f) * * * *
* * * *
g) * * * *
* * * *
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In this way, we can go on and multiply 5-digit, 6-digit, 7-digit and bigger numbers
But rather than doing examples of every type, I will give you a simple formula that you can use for all such numbers.
By learning the formula, you will be able to do any multiplication problem.
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FORMULA
The number of steps to be used in any multiplication technique can be found out by using the formula
‘2 x (number of digits) – 1’
• Thus, when we multiplied 2-digit numbers, the steps used are
2 x 2 – 1 = 3
• When we multiply 3-digit numbers, the steps used are 2 x 3 – 1 = 5
• When we multiply 4-digit numbers, the steps used are
2 x 4 – 1 = 7
![Page 34: Criss-Cross Multiplication.pdf](https://reader035.vdocuments.us/reader035/viewer/2022081801/55cf9b0c550346d033a4889d/html5/thumbnails/34.jpg)
Just go a few slides back and carefully observe the notation of steps used in 2-digit, 3-digit and 4-digit numbers.
They follow a particular trend..
You can expand the same trend to multiply higher order numbers..