The snacks sold in small stalls around the school are called "5jiao snacks". Among them, there is a 5-corner snack that is marked on the package as 90 grams, but it is 0.060 kilograms with an electronic scale. How many kilograms is the difference between the marked weight and the actual weight.
学校周边的小摊子卖的零食称为"5角零食"．其中有一种5角零食包装上标示的重是90克，但用电子秤称是0.060千克．标示的重量与实际重量相差多少千克．
<gadget id="calculator">90 / 1_000</gadget>
<output>9/100 = around 0.09</output>

<gadget id="calculator">(9/100) - 0.06</gadget>
<output>0.03</output>

<result>0.03</result>