Given that 2.45*1.09+0.245*9.1-0.245*10.9-0.0245*91+0.00245*1090+0.000245*9100=b, find the value of b.
已知2.45*1.09+0.245*9.1-0.245*10.9-0.0245*91+0.00245*1090+0.000245*9100=b，求b的值．
<gadget id="calculator">2.45 * 1.09</gadget>
<output>2.6705</output>

<gadget id="calculator">0.245 * 9.1</gadget>
<output>2.2295</output>

<gadget id="calculator">0.245 * 10.9</gadget>
<output>2.6705</output>

<gadget id="calculator">0.0245 * 91</gadget>
<output>2.2295</output>

<gadget id="calculator">2.2295 - 2.6705 - 2.2295</gadget>
<output>-2.6705</output>

<gadget id="calculator">0.00245 * 1_090</gadget>
<output>2.6705</output>

<gadget id="calculator">0.000245 * 9_100</gadget>
<output>2.2295</output>

<gadget id="calculator">2.6705 + (-2.6705) + 2.6705 + 2.2295</gadget>
<output>4.9</output>

<result>4.9</result>