In the previous tutorial on multiplication of any 2-digit number, we learnt how to multiply any 2-digit numbers using criss-cross method of multiplication.
In this tutorial, we will understand a very important mathematical shortcut of multiplying any two 3 digit numbers using the criss-cross multiplication technique.
For students preparing for competitive examination, You might come across, many multiplications in the competitive examinations where you might be asked to multiply two 3-digit number.
If you know criss-cross method, you can save a lot of time by eliminating the choices at the end of each step of criss-cross multiplication.
The number of steps in a 3 x 3 multiplication is 5. Let’s understand the steps with an example.
Example : Suppose you want to multiply 132 x 214.
Step 1 : Write the numbers one below the other. Multiply the digits in the unit place as in 2×2 multiplication, that is 2×4=2. This will be the unit digit of the answer as well.
Step 2 : Now, cross multiply the digits in the 10’s and unit’s place to get the digit in the 10’s place of the answer.
Step 3 : Now, notice the criss-cross multiplication. Here, we multiply the terms (1×4), (2×2) and (3×1) and then add these terms to get 11.
Step 4 : Now, repeat Step 2 with the digits in the 100’s and the 10’s place.
Step 5 : This is the last step in the multiplication. Now, repeat Step 1 with the digits in 100’s place.
The complete steps involved in the calculation is illustrated in the figure :
Notice the carry-forward in each step.
On the similar lines, can you multiply,
- 423 x 234
- 124 x 465
- 567 x 890
- 646 x 772
I hope this tutorial is useful. If you have any doubts concerning this tutorial, please leave a comment, I would be glad to help.