what is the list of android version number

Here's the list you want

Cupcake:
Android 1.5

Donut:
Android 1.6

Eclair:
Android 2.0
Android 2.1

Froyo: (short for "frozen yogurt")
Android 2.2

Gingerbread:
Android 2.3

Honeycomb:
Android 3.0
Android 3.1
Android 3.2

Ice Cream Sandwich:
Android 4.0

Jelly Bean:
Android 4.1
Android 4.2
Android 4.3

KitKat:
Android 4.4

Lollipop:
Android 5.0
Android 5.1

Marshmallow:
Android 6.0

Here is the dashboard about Platform Versions:

http://developer.android.com/about/dashboards/index.html