Evaluate the following using suitable identities:

(i) (99)³

(ii) (102)³

(iii) (998)³

Verify :

(i) x³ + y³ = (x + y) (x² - xy + y²)

(ii) x³ - y³ = (x - y) (x² + xy + y²)

Factorise each of the following:

(i) 27y³ + 125z³

(ii) 64m³ - 343n³