Find the cubes of:

(i) 

Cube of $-11$ is given as:

$(-11)^{3}=-11 \times-11 \times-11=-1331$

Thus, the cube of 11 is $(-1331)$.

(ii) 

Cube of $-12$ is given as:

$(-12)^{3}=-12 \times-12 \times-12=-1728$

Thus, the cube of $-12$ is $(-1728)$.

(iii)

Cube of $-21$ is aiven as:

$(-21)^{3}=-21 \times-21 \times-21=-9261$

Thus, the cube of $-21$ is $(-9261)$.