How do you determine the number of zeros to annex in the product of 0.002 and 0.003?

0.002 x 0.003 = 0.000006

the zeroes are multiplied by the power of 10 which is 1/10 in particular.
For example.
The product of a whole number and a decimal number less than 1 will be greater than the whole number multiplied into. For this theorem to be proven. Let us state the mathematical expression into numbers such that 
1.  N x 0.1 = N/0.1 < N 
2.  1 x 0.5 = 0.5 
3.  2 x 0.1 = 0.2 
4.  100 x 0.55 = 55  

These three examples and stances then suggest the claim that the product is not equal to the whole number used in the equation.