A workshop plans to complete the task of processing a batch of parts in 5 days. On the first day, (1/5) more than 120 pieces of this batch of parts were processed, and on the second day, the remaining (1/4) was processed by 150 pieces less. The remaining (1/3) was processed with 80 more in three days, the remaining (1/2) was processed with 20 less on the fourth day, and the last 1800 were processed in the fifth day. How many parts are there in total in this batch?
一个车间计划用5天完成加工一批零件的任务，第一天加工了这批零件的(1/5)多120个，第二天加工了剩下的(1/4)少150个，第三天加工了剩下的(1/3)多80个，第四天加工了剩下的(1/2)少20个，第五天加工了最后的1800个．这批零件总数有多少个？
<gadget id="calculator">1_800 - 20</gadget>
<output>1_780</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

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

<gadget id="calculator">1_780 / (1/2)</gadget>
<output>3_560</output>

<gadget id="calculator">3_560 + 80</gadget>
<output>3_640</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 - (1/3)</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">3_640 / (2/3)</gadget>
<output>5_460</output>

<gadget id="calculator">5_460 - 150</gadget>
<output>5_310</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">5_310 / (3/4)</gadget>
<output>7_080</output>

<gadget id="calculator">7_080 + 120</gadget>
<output>7_200</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">7_200 / (4/5)</gadget>
<output>9_000</output>

<result>9_000</result>