Fill in the blanks with the correct steps for solving:

(3.71 * 10 ^ 5) + (4.65 * 10 ^ 7)

= (3.71 * 10 ^ 5) + (46.5 * 10 ^ 6)

= (37.1 * 10 ^ 4) + (465 * 10 ^ 5)
= 502.1 * 10 ^ 4