Question:
Tick (✓) the correct answer:
(197 × 203) = ?
(a) 39991
(b) 39999
(c) 40009
(d) 40001
Solution:
(a) 39991
$(197) \times(203)$ [using the identity (a+b) (a-b) = a2 -b2]
$\Rightarrow(200-3)(200+3)$
$\Rightarrow(200)^{2}-(3)^{2}$
$\Rightarrow 40000-9$
$\Rightarrow 39991$