To divide 166.4 by 0.52, you need to eliminate the decimal in the divisor (0.52).
To do this, you would move the decimal in 0.52 two places to the right, making it 52. To keep the division equivalent, you must also move the decimal in 166.4 the same number of places (2 places) to the right, turning it into 16640.
So, the final answer is 2 places.