Chapter 7 - Exponents and Exponential Functions - 7-3 Multipying Powers with the Same Base - Practice and Problem-Solving Exercises - Page 430: 56

$1.5 \times 10^{8}$

$a^m \cdot a^n = a^{m+n}$ Multiply the corresponding parts and use the rule above when necessary to obtain: $=(0.5\cdot 0.3) \times (10^{13} \cdot 10^{-4}) \\=0.15 \times 10^{13+(-4)} \\=0.15 \times 10^{9} \\=1.5(10^{-1}) \times 10^{9} \\=1.5 \times 10^{-1+9} \\=1.5 \times 10^{8}$