Answer
$-56$
Work Step by Step
We start with the given expression: $(7i)(8i)$
We regroup the real and imaginary terms using the associative and commutative properties of multiplication: $(7\times8)(i\times i)$
We multiply the real and imaginary terms: $56i^2$
Since $i^2$ is equal to $-1$, we simplify the expression as follows: $56\times-1=-56$
