Squares of which of the following numbers will have 1 (one) at their unit's place:
(i) 57 (ii) 81
(iii) 139 (iv) 73
(v) 64
Evaluate:
(i) 53 × 55; (ii) 102 × 106; (iii) 34 × 36; (iv) 103 × 96.