Question 905469
<pre>
This is 30 small squares (left to right) by 40 small squares (top to bottom) rectangle.
Each of the 3 large red squares (left to right) is 10 small squares (left to right) by 10 small squares (top to bottom).

There are 30x40 or 1200 small squares. 

{{{drawing(18600/41,600,-.5,30.5,-.5,40.5,

red(line(0,0,0,40)),
green(line(1,0,1,40)),
green(line(2,0,2,40)),
green(line(3,0,3,40)),
green(line(4,0,4,40)),
green(line(5,0,5,40)),
green(line(6,0,6,40)),
green(line(7,0,7,40)),
green(line(8,0,8,40)),
green(line(9,0,9,40)),
red(line(10,0,10,40)),
green(line(11,0,11,40)),
green(line(12,0,12,40)),
green(line(13,0,13,40)),
green(line(14,0,14,40)),
green(line(15,0,15,40)),
green(line(16,0,16,40)),
green(line(17,0,17,40)),
green(line(18,0,18,40)),
green(line(19,0,19,40)),
red(line(20,0,20,40)),
green(line(21,0,21,40)),
green(line(22,0,22,40)),
green(line(23,0,23,40)),
green(line(24,0,24,40)),
green(line(25,0,25,40)),
green(line(26,0,26,40)),
green(line(27,0,27,40)),
green(line(28,0,28,40)),
green(line(29,0,29,40)),
red(line(30,0,30,40)),
red(line(0,0,30,0)),
green(line(0,1,30,1)),
green(line(0,2,30,2)),
green(line(0,3,30,3)),
green(line(0,4,30,4)),
green(line(0,5,30,5)),
green(line(0,6,30,6)),
green(line(0,7,30,7)),
green(line(0,8,30,8)),
green(line(0,9,30,9)),
red(line(0,10,30,10)),
green(line(0,11,30,11)),
green(line(0,12,30,12)),
green(line(0,13,30,13)),
green(line(0,14,30,14)),
green(line(0,15,30,15)),
green(line(0,16,30,16)),
green(line(0,17,30,17)),
green(line(0,18,30,18)),
green(line(0,19,30,19)),
red(line(0,20,30,20)),
green(line(0,21,30,21)),
green(line(0,22,30,22)),
green(line(0,23,30,23)),
green(line(0,24,30,24)),
green(line(0,25,30,25)),
green(line(0,26,30,26)),
green(line(0,27,30,27)),
green(line(0,28,30,28)),
green(line(0,29,30,29)),
red(line(0,30,30,30)),
green(line(0,31,30,31)),
green(line(0,32,30,32)),
green(line(0,33,30,33)),
green(line(0,34,30,34)),
green(line(0,35,30,35)),
green(line(0,36,30,36)),
green(line(0,37,30,37)),
green(line(0,38,30,38)),
green(line(0,39,30,39)),
red(line(0,40,30,40))

)}}}

Edwin</pre>