Question

Question 86 (xiv)

Using suitable identities, evaluate the following:

$9.8\times 10.2$

Answer 1

We have,
$9.8\times 102=(10-0.2)(10+0.2)={10}^2-(0.2{)}^2=100-0.04=100-0.04$
$=99.96$ [using the identity, $(a+b)(a-b)=a^2-b^2$]