10
4 inches = 10.16 cm
As many as you want to. None can be bigger than 4 cm by 4 cm, but they can be as small as you want, and there's no limit to the number you can draw in there.
10 cm
1 inch = 2.54cm so 4 inches are 2.54 * 4 or 10.16cm
4 m = 400 cm
9' 4" = 284.5 cm
4 in = 4 x 2.54 cm = 10.16 cm
400 cm
4 mm = 0.4 cm
0.25
450 cm.
4 cm * 4 cm = 16 sq cm