The scientific notation of 673.5 is 6.735 x 10^2. In the scientific notation, a large number is written in two parts. The first part is the number from 1 to 9 and the second part is 10 to a power. For example, 2,000 can be written as 2 x 10^3 because 2,000 = 2 x 1,000 = 2 x 10^3. So, 673.5 = 6.735 x 100 = 6.735 x 10^2.