This worked chemistry example problem demonstrates how to convert from metric units to different metric units.
When one gram of gasoline burns in a car's engine, the amount of energy given off is approximately 1.03 x 104 cal. Express this quantity in joules.
1 cal = 4.184 J
To convert calories to joules, use the conversion factor 4.184 J / 1 cal.
1.03 x 104 cal x 4.184 J / 1 cal = 4.31 x 104 J
4.31 x 104 J (note that 3 significant figures are used to report the answer)