Multiply any 2 digit numbers

 

In this tutorial, we are going to learn the shortcut how to multiply any 2 digit numbers.  This method of multiplication is called Criss-Cross method of multiplication.

If both the multiplicand and the multiplier is a 2-digit number, you can get the answer in 3 steps.

Let’s explain with an example.  Suppose you want to multiply 32×21.

Let’s understand the steps involved.

Step 1 :  Multiply the digits in the unit place, that is 2×1=2. This will be the unit digit of the answer as well.

 

criss-cross1

 

Step 2 :  Now this is important. Now, we cross-multiply the numbers 3×1=2 and 2×2=4 and add them. This is why it is referred to as  the term criss-cross multiplication. Write 7 in the 10’s place of the answer.

 

criss-cross2

 

Step 3 :  This is the last step. You just multiply the digits in the 10’s place, that is 3×2=6.

 

criss-cross3

So, the product will be :

criss-cross4

 

The complete steps involved in the calculation can be illustrated in the following figure.

 

criss-cross5

 

If you practice this shortcut, you can multiply the any 2 -digit numbers mentally without actually doing any computation.

Let’s take another example.  Let’s consider the multiplication 47×32. The complete steps involved in the calculation is illustrated in the figure:

criss-cross6

 

Notice the carry-forward in each step. It is important to note that only 1 digit should be retained in each steps. The rest is carry forward.

 

Important Note :

Number of steps involved in the criss-cross multiplication  = 2x(number of digits) – 1

  • For 2-digit multiplication, number of steps : 2×2- 1 = 3
  • For 3-digit multiplication, number of steps : 2×3- 1 = 5
  • For 4-digit multiplication, number of steps : 2×4- 1 = 7

 

Easy 🙂 ?

 

Exercise : On the similar lines, can you multiply,

  • 18 x 19
  • 72 x 43
  • 92 x 99
  • 56 x 65

 

I hope this tutorial is useful. If you have any doubts concerning this tutorial, please leave a comment, I would be glad to help.

Kiran Chandrashekhar

Hey, Thanks for dropping by. My name is Kiran Chandrashekhar. I am a full-time software freelancer. I love Maths and Mathematical Shortcuts. Numbers fascinate me. I will be posting articles on Mathematical Shortcuts, Software Tips, Programming Tips in this website. I love teaching students preparing for various competitive examinations. Read my complete story.

6 Comments

  1. wow, awesome blog article.Really looking forward to read more. Awesome.

  2. The example was simple and neatly done. Finally able to do 2 digits, although 3 digits was a easy for me, I don’t know why. Have a good one!

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