Tricks for faster calculations - Squares of 2 digit numbers

Let ab be the number. i.e. Digit at Ten's place be a and digit at Unit's place be b.
1) Calculate square of a. Put 2 dots(..) to it's right.
2) Calculate 2 x a x b. Put 1 dot and write below above number such that right most dots in both steps are one below the other.
3) Now calculate square of b and write its unit place's digit below the right most dot written in step 2). Write rest of number below units place digit of number written in step 2)
4) Make simple addition. Treat dots as ZEROS.

Ex. 89^2
1) 8 x 8 =64 ------------------- 6 4  .  .
2) 2 x 8 x 9 = 144-------------- 1 4 4  .
3) 9 x 9 = 81 ------------------        8 1
-------------------------------------------
                                                  7 9 2 1
4) Add to get required square.