If the number is between 0 and 1, and we are writing it in scientific notation, the exponent of the power of 10 is going to be smaller than 0 (that is a negative number for the exponent)
This is because the number of powers of ten are going to be part of a denominator.
For example, the number 0.001 which is between zero and 1 , can be written as:
1 divided by 1000. Notice then the 1000 value is in the denominator. powers of 10 in the denominator are represented always with negative exponents when written in scientific notation.
Anotther example is shown below:
Again, the exponent of the power 10 will be a negative integer number in scientific notation.