Ancient Greek mathematicians called the numbers 1, 3, 6, 10, 15, 21, ... Triangular numbers, which have certain regularity, what is the difference between the 100th triangular number and the 98th triangular number?
古希腊数学家把数1，3，6，10，15，21，…，叫做三角形数，它有一定的规律性，则第100个三角形数和第98个三角形数的差为多少．
<gadget id="calculator">100 + 99</gadget>
<output>199</output>

<result>199</result>