Let A=1*2+2*3+3*4+…+98*99+99*100 and B=1**2+2**2+3**2+…+98**2+99 **2. So how much is AB=.
令A=1*2+2*3+3*4+…+98*99+99*100且B=1**2+2**2+3**2+…+98**2+99**2．那么A-B=多少．
<gadget id="calculator">5 + 197</gadget>
<output>202</output>

<gadget id="calculator">49 / 2</gadget>
<output>49/2 = around 24.5</output>

<gadget id="calculator">202 * (49/2)</gadget>
<output>4_949</output>

<gadget id="calculator">1 + 4_949</gadget>
<output>4_950</output>

<result>4_950</result>