Square of any 2 digit numberLet me explain this trick by taking examples 67^2 = [6^2][7^2]+20*6*7 = 3649+840 = 4489 similarly 25^2 = [2^2][5^2]+20*2*5 = 425+200 = 625 Take one more example 97^2 = [9^2][7^2]+20*9*7 = 8149+1260 = 9409 Here [] is not an operation, it is only a separation between initial 2 and last 2 digits