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).
6.85179595.5
Step 2: We moved the decimal point 8 spaces to the right. Therefore, the exponent on base 10 will be positive 8.Now we know that the:
Mantissa = 6.851795955
Exponent = 8
So, the solution is:
$$685179595.5 = \color{blue}{ 6.851795955} \cdot 10^{ \color{red}{ 8 }}$$