Squaring a number

Got this from www.tenaday.com - good trick that can easily be practised.

Square of XYZ = ?
STEP 1: Last digit = last digit of SQ(Z)
STEP 2: Second Last Digit = 2*Y*Z + any carryover from STEP 1.
STEP 3: Third Last Digit = 2*X*Z+ SQ(Y) + any carryover from STEP 2.
STEP 4: Fourth last digit = 2*X*Y + any carryover from STEP 3.
STEP 5: In the beginning of result will be SQ(X) + any carryover from Step 4.

Ex: Square of 523 = ? Here, X = 5, Y = 2 and Z = 3
STEP 1: Last digit = last digit of SQ(3) = 9
STEP 2: Second Last Digit = 2*2*3 + 0 (carryover from Step 1) = 12
STEP 3: Third Last Digit = 2*5*3+ SQ(2) + 1 = 35
STEP 4: Fourth last digit = 2*5*2 + 3 = 23
STEP 5: In the beginning of result will be SQ(5) + 2 =27

Therefore, Square of 523= 273529