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).
0.006.4
Step 2: We moved the decimal point 3 spaces to the left. Therefore, the exponent on base 10 will be negative 3.Now we know that the:
Mantissa = 6.4
Exponent = -3
So, the solution is:
$$0.0064 = \color{blue}{ 6.4} \cdot 10^{ \color{red}{ -3 }}$$