Shortcut to multiply any 2 digit number by 15

 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 

---

Example 3:32 x 15 = ?
Step 1:We find that half of the number is
32/2 = 16

Step 2: Adding the given number and the result obtained in step 1
we get 32 + 16 = 48

Step 3:Placing zero next to step 2
we get 480

Example 4:74 x 15 = ?
Step 1:We find that half of the number is
74/2 = 37

Step 2: Adding the given number and the result obtained in step 1
we get 74 + 37 = 111

Step 3:Placing zero next to step 2
we get 1110

Ans 74 x 15 = 1110 

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