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Evaluate each of the following using identities:$991 \times 1009$
Given:
$991 \times 1009$
To do:
We have to evaluate the given expression using a suitable identity.
Solution:
We know that,
$(a+b)^2=a^2+b^2+2ab$
$(a-b)^2=a^2+b^2-2ab$
$(a+b)(a-b)=a^2-b^2$
Therefore,
$991 \times 1009=(1000-9)(1000+9)$
$=(1000)^{2}-(9)^{2}$
$= 1000000-81$
$=999919$
Hence, $991 \times 1009=999919$.
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