After Xiao Ming used a calculator to calculate the average of 1998 numbers, he accidentally mixed the average with the original 1998 numbers. Interestingly, the average of these 1999 numbers is exactly 1999. What is the average of the original 1998 numbers?
小明在使用计算器计算1998个数的平均数后，不小心把所求的平均数与原先的1998个数混在了一起．有趣的是，这1999个数的平均数恰好是1999．原先这1998个数的平均数是多少．
<gadget id="calculator">1_999 * 1_998</gadget>
<output>3_994_002</output>

<gadget id="calculator">3_994_002 + 1_999</gadget>
<output>3_996_001</output>

<gadget id="calculator">1_998 + 1</gadget>
<output>1_999</output>

<gadget id="calculator">3_996_001 / 1_999</gadget>
<output>1_999</output>

<result>1_999</result>