Respuesta :

[tex]7\cdot10^3\cdot5\cdot10^8=(7\cdot5)\cdot(10^3\cdot10^8)\text{ = 35}\cdot10^{3+8}=35\cdot10^{11}[/tex]

The student is off by a power of ten. The correct product is 35 x 10^11 or 3.5 x 10^12