Answer:
Single digit natural number can't be write in scientific notation.
We write very large and long positive number into scientific notation because it's easy to read.
We can't write negative number into scientific notation.
Explanation:
Single digit natural numbers are 1,2,3,4,5,6,7,8,9
Scientific Notation:

where,
k is between 1 to 9 , i,e

n is any integers.
Example: Write in scientific notation
1) 5869742000
Scientific Notation:

2) 0.000000849
Scientific Notation:
