Squaring a number ending with 5

I have realised that exposure to vedic mathematics short cut methods is essential for students for improving their mental mathematics skill. In my free class period I show them the videos on how to use these tricks.After that I give them practice questions.
This video is explaining a short cut method to find the square of a number ending with 5 using a vedic mathematics sutra

This means "By one more than the previous one"
I am sharing one example how this sutra is applied?
65^2= [6 X (6+1)] 25 = 4225
For this number , the last digit is 5 and the 'previous' digit is 6. Hence, 'one more than the previous one', that is, 6+1=7.
The Sutra, in this context, gives the procedure 'to multiply the previous digit 6 by one more than itself, that is, by 7'. It becomes the L.H.S of the result, that is, 6 X 7 = 42.
The R.H.S of the result 25..