Step 1: Move the decimal point from its current position (the black dot) to a position immediately to the right of the first nonzero digit (the red dot).
0.00000001.8
Step 2: We moved the decimal point 8 spaces to the left. Therefore, the exponent on base 10 will be negative 8.Now we know that the:
Mantissa = 1.8
Exponent = -8
So, the solution is:
$$0.000000018 = \color{blue}{ 1.8} \cdot 10^{ \color{red}{ -8 }}$$