Choose two numbers from 1 to 500, and the sum is a multiple of 100. How many ways are there?
1～500选两个数，和是100的倍数，一共有多少种方法？
<gadget id="calculator">99 * 5</gadget>
<output>495</output>

<gadget id="calculator">100 * 4</gadget>
<output>400</output>

<gadget id="calculator">100 * 3</gadget>
<output>300</output>

<gadget id="calculator">100 * 2</gadget>
<output>200</output>

<gadget id="calculator">50 * 1</gadget>
<output>50</output>

<gadget id="calculator">495 + 400 + 300 + 200 + 50</gadget>
<output>1_445</output>

<result>1_445</result>