#### Answer

$9i$

#### Work Step by Step

Step 1: $\sqrt 27\times\sqrt -3$
Step 2: $\sqrt (27\times-3)$
Step 3: $\sqrt (-81)$
Step 4: $\sqrt -1\times\sqrt 81$
Step 5: As $\sqrt -1=i$, the expression becomes $i\sqrt 81$
Step 6: Simplifying further, the expression becomes $i(9)$ or $9i$