Shortcut to multiply any 2 digit number by 15

An interesting way to multiply a 2 digit number by 15. This can be used when the given number is easily divisible by 2.





Lets now go through the steps

Step 1: Find half of the given number.

Step 2:Now add the given number and the result obtained in step 1.

Step 3:Multiply the result obtained in step 2 by 10.


Now let us consider a few examples to understand better

Example 1: 12 x 15 = ?
Step 1:We find that half of the number is
            12 /2 = 6

Step 2: Adding the given number and the result obtained in step 1
            we get 12 + 6 = 18

Step 3:Multiplying the result obtained in step 2 by 10
            we get 180

Ans 12 x 15 = 180




Example 2:48 x 15 = ?
Step 1:We find that half of the number is
            48 /2 = 24

Step 2: Adding the given number and the result obtained in step 1
            we get 48 + 24 = 72

Step 3:Placing zero next to step 2
            we get 720

Ans 48 x 15 = 720

Now you try applying this trick to multiply 25, 72 ,43,57 by 15 in secs 



     
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