Do you mean...,
8.60 X 10^(-3)
or
8.60 X 10^3
?
If I do not hear back from you by tomorrow I'll do this simple combustion problem both ways, but you could save me the work by using the proper notation. This...^...means to raise to a power.
======
First the balanced equation,
CH4 + 2O2 --> CO2 + 2H2O
------First, 8.60 X 10^(-3) g
8.60 X 10^(-3) g (1 mole CH4/16.042 g)(2 mole O2/1 mole CH4)(32 g/1 mole O2)
= 0.034 grams oxygen
======Now, 8.60 X 10^3 g
8.60 X 10^3 g (1 mole CH4/16.042 g)(2 mole O2/1 mole CH4)(32 g/1 mole O2)
= 3.43 X 10^4 grams oxygen
======Both ways.