The moisture content of 4 tons of grapes in Xinjiang was measured at 99%, and the moisture content was measured at 98% after they arrived in Nanjing. How many tons of grapes are left after they arrive in Nanjing?
4吨葡萄在新疆测得含水量99%，运抵南京后测得含水量是98%，问葡萄运抵南京后还剩几吨？
<gadget id="calculator">99 / 100</gadget>
<output>99/100 = around 0.99</output>

<gadget id="calculator">1 - (99/100)</gadget>
<output>1/100 = around 0.01</output>

<gadget id="calculator">98 / 100</gadget>
<output>49/50 = around 0.98</output>

<gadget id="calculator">1 - (49/50)</gadget>
<output>1/50 = around 0.02</output>

<gadget id="calculator">(1/100) / (1/50)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">4 * (1/2)</gadget>
<output>2</output>

<result>2</result>