Let us take a 2 digit number ending in 5 i.e 45

Now (45)²

Step 1: multiply the digit at tens place by a number 1 greater than that i.e.4*5 =20

Step 2: write 25 after the multiplication i.e. 2025

Hence,(45)² =2025

Lets try it with a different two digit number ending in 5 i.e. 65

(65)²= (6*7)/25=4225 (done in 3 seconds or may be lesser than that)

Hope you enjoyed

Now try to do it with

1)85

2)55