Which number is the largest? 7.2 ⋅ 10−6, 3.09 ⋅ 103, 2.04 ⋅ 104, 5 ⋅ 103 7.2 ⋅ 10−6 3.09 ⋅ 103 2.04 ⋅ 104 5 ⋅ 103