A workshop produces parts. The monthly plan (1/3) is completed in the first ten days of May, and the monthly plan (2/5) is completed in the middle of May. Exactly 1650 pieces have been completed. How many pieces are the monthly plan?
某车间生产零件，五月份上旬完成月计划的(1/3)，中旬完成月计划的(2/5)，正好完成了1650件，求月计划是多少件？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(1/3) + (2/5)</gadget>
<output>11/15 = around 0.733333</output>

<gadget id="calculator">1_650 / (11/15)</gadget>
<output>2_250</output>

<result>2_250</result>