Which step is incorrect in adding 4.5 × 10⁷ and 3.2 × 10⁶?

Result is 4.82 × 10⁷.

Adjust 4.5 × 10⁷ to match the smaller exponent.

Add the coefficients 4.5 and 0.32.

Adjust 3.2 x 10⁶ to 0.32 × 10⁷.