Squaring a 2 digit number - revisited

When my husband and I were playing around with the nos, he discovered a new smart shortcut to find squares of nos.

Example : 69

1. Add the unit digit '9' to the no itself

9+69= 78

2. Multiply this with the ten s digit '6' of the original no

6*78=468

3. Square the unit s digit of the original no and append at the end after shifting it once to left

4680 || 9^2 = 4680 || 81 = 4761

This method can very well be extended to higher digit nos too !