The scientific way to write 0.00000000000000000000000000000000000039 is:

3.9 x 10^-34

Here's how it works:

* 3.9: This is the coefficient, a number between 1 and 10.

* 10: This is the base of the power of ten.

* -34: This is the exponent, indicating how many places to move the decimal point to the left.

This notation is called scientific notation and is widely used in science to represent very large or very small numbers in a concise and manageable way.