Question

Last question I can’t

Answer 1

I think this will be helpful to you

Answer 2

ANSWER.

(1)

$101 \times 99 = (100 + 1)99$

$9900 + 99$

$9999$

(2)

$53 \times 47$

$= (50 + 3)(50 - 3)$

${50}^{2} - {3}^{2}$

$2500 - 9$

$2491$

(3)

${121}^{2} - {119}^{2}$

${(120 + 1)}^{2} - {(120 - 1)}^{2}$

Using formula

${a}^{2} - {b}^{2} = (a - b)(a + b)$

$(120 + 1 + 120 - 1)(120 + 1 - 120 +1)$

$240 \times 2$

$480$

(4)

$\frac{(23.71 \times 23.71) - (16.29 \times 16.29)}{0.742}$

using identity

${a}^{2} - {b}^{2} = (a - b)(a + b)$

$\frac{ {(40.00)}- {(7.42)}}{0.742}$

=400 ans