Question
Use the product $(a + b) (a – b) = a^2 – b^2$ to evaluate : $7.7 \times 8.3$
✓
Answer
$7.7 \times 8.3 $
$= (8−0.3) (8+0.3)$
$= (8)^2− (0.3)^{2 }$
$= 64 − 0.09$
$= 63.91$
$= (8−0.3) (8+0.3)$
$= (8)^2− (0.3)^{2 }$
$= 64 − 0.09$
$= 63.91$
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