Short-cut to find square of any number

Eg 1) 36²   
Step 1: Choose the base number.36 is closer to 40. Therefore 40 is the base number.
Step 2:Find how much the given number is more or less of the base number.36 is  -4 of 40.
Step 3: Square the difference. (-4)² =16.
Step 4: Add the difference to the given number. 36-4=32.
Step 5: Multiply the above result with the base number. 32 x 40 =1280.
Step 6: Add the result of step 3 with the result of step 5.
1280 + 16=1296.
Ans: 1296.
Let’s do with another one.
Eg 2) 62²
Step 1: Base number is 60.
Step 2: 62-60=2.
Step 3: 2²=04 (Write 0 in the ten’s place if the square is a single digit)
Step 4: 62+ 2=64.
Step  5: 64 x 60=3840
Step 6: 3840 + 04=3844
Ans:3844.
Eg 3) 79²
Step 1: Base number is 80.
Step 2: 79-80 =-1.
Step 3: (-1)²=01
Step 4: 79-1=78.
Step 5: 78 x 80=6240.
Step 6: 6240 + 01=6241.
Eg 4) 84²
Step 1: 80 is the base
Step 2: 84-80 =4
Step 3: (4)²=16
Step 4:84 + 4=88
Step 5: 88 x 80=7040
Step 6: 7040+16=7056
Eg 5) 77²
Step 1: 80 is the base number.
Step 2: 77-80=-3
Step 3: (-3)²=09
Step 4: 77-3=74
Step 5: 74 x 80 =5920
Step 6:5920 + 09=5929
Eg 6) 49²
Step 1: 50 is the base number.
Step 2: 49-50=-1
Step 3: (-1)²=01
Step 4: 49-1=48
Step 5: 48 x 50=2400
Step 6: 2400 + 01=2401