John likes 400 but not 300 he likes 100 but not 99 he likes 3600 but not 3700 Which does he like 900 1000 1100 1200?

John likes 1100. 900.

He likes 400 but not 300; 400 is the square of an integer (20) but 300 is not.

He likes 100 but not 99; 100 is the square of an integer (10) but 99 is not.

He likes 3600 but not 3700; 3600 is the square of an integer (60) but 3700 is not.

900 is the square of an integer (30), but 1000, 1100, and 1200 are not.