Question

Using suitable identities, evalute $497\times 505$.

• A. 250190
• B. 250998
• C. 250985
• D. 259085

Answer 1

The correct option is C 250985

$497\times 505=(500-3)(500+5)$
$={500}^2+(-3+5)\times 500+(-3)\left(5\right)$
$\left[using\right(x+a\left)\right(x+b)=x^2+(a+b)x+ab]$
$=250000+1000-15$
$=250985$