In this case, we'll have to carry out several steps to find the solution.
Step 01:
cost per square
1
0.1
0.01
0. 001
Step 02:
cost of the rectangle
1 ===> 1 * 1 = 1
0.1 ===> 0.1 * 0.1 = 0.01
0.01 ===> 0.01 * 0.01 = 0.0001
0. 001 ===> 0.001 * 0.001 = 0.000001
That is the solution.