Aunt Wang deposits 100 yuan in the bank, and the annual interest rate is 2.25%. How much after-tax interest can she get after one year?
王大妈存入银行100元钱，年利率是2.25%，一年后可得税后利息多少元．
<gadget id="calculator">2.25 / 100</gadget>
<output>0.0225</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">100 * 0.0225 * 1 * (4/5)</gadget>
<output>1.8</output>

<result>1.8</result>