John likes 400 but not 300; he likes 100 but not 99; he likes 3600 but not 3700. Which does he like? ?

Question

900

1000

1100

1200

??

Answer 1

1000

Answer 2

900.  All the numbers he likes are perfect squares

400 = 20^2

100= 10^2

3600 = 60^2

900= 30^2

Answer 3

900

cuz all the numbers he like are squares of a number that's to say perfect square!

Answer 4

1200?????

Answer 5

1000

1200

Addendum: Thanks guys.  I got it wrong, but at least I know why it's wrong now.

Answer 6

Perfect squares:

400 = 20 * 20

100 = 10 * 10

3600 = 60 * 60

900 = 30 *30

So, 900.

lol At the beggining I thought the numbers were nicknames for people... I know, random.