Answer :
This is simply:
8 * 10⁷ * 2 * 10⁶
8 * 2 * 10⁷ ⁺ ⁶
16 * 10¹³
1.6 * 10¹ * 10¹³
1.6 * 10¹ ⁺ ¹³ = 1.6 * 10¹⁴
Option D.
8 * 10⁷ * 2 * 10⁶
8 * 2 * 10⁷ ⁺ ⁶
16 * 10¹³
1.6 * 10¹ * 10¹³
1.6 * 10¹ ⁺ ¹³ = 1.6 * 10¹⁴
Option D.