From the natural numbers from 1 to 100, take two numbers at a time and require their sum to be greater than 100. How many ways are there?
从1到100的自然数中，每次取两个数，要求他们的和大于100，有多少种取法．
<gadget id="calculator">50 * 49</gadget>
<output>2_450</output>

<gadget id="calculator">2 * 1</gadget>
<output>2</output>

<gadget id="calculator">2_450 / 2</gadget>
<output>1_225</output>

<gadget id="calculator">50 * 51</gadget>
<output>2_550</output>

<gadget id="calculator">2_550 / 2</gadget>
<output>1_275</output>

<gadget id="calculator">1_225 + 1_275</gadget>
<output>2_500</output>

<result>2_500</result>