**Square of a two-digit number:**

**Quick Method:**

(82)^{2}= 6404

32 [8*2*2] ==> 8 and 2 from original number itself and another 2 from the power of 82 i.e. 2

6724

**Likewise for square of 79:**

(79)^{2}= 4981

126 [7*9*2]

6241 ==> Final Answer

**Likewise for square of 63:**

(63)^{2}

= 3609

+ 36

= 3969 ==>Final Answer