When you will know this awesome trick, then you will be able to perform the multiplication of two 2digit numbers easily without using a calculator. Let's understand how to perform this by taking the example 31 x 12.

Multiply the ones digit vertically

Multiplying in a cross pattern and adding the results.

Multiplying the tens digit vertically.
This is how one can calculate the product of two 2digit numbers easily.
Important Note :
If while performing the second step, cross multiplication and addition, the results appears to be twodigit number take carry the 10's digit and add it to step 3. Example
in 34 * 34 the second step would result in 24 so 2 will be carried and added to step 3.
Try some problems on your own.
 34*34
 23*12
 10*17