Question

what should be multiplied 3to the power of -5 so that the product you get is 81

Answer 1

let the number be z 
then 3⁻⁵×z×=81

we know that 81= 3⁴

so z=3⁹ i.e 19683

Answer 2

You can write 3 raise to -5 as 1 upon 3 raise to 5
the answer comes out to be 1/243
Let your final answer be X
so 1/243 * X =81
X = 243*81=19683
Your final answer X=19683