Teacher Li is depositing 18,000 yuan in the bank for a period of 3 years. If the annual interest rate is 2.7%, 20% interest tax should be paid, how much is the principal and after-tax interest in total after the maturity date?
李老师在把18000元存入银行，定期3年．如果年利率是2.7%，应缴20%的利息税，到期后他得本金和税后利息共多少元？
<gadget id="calculator">2.7 / 100</gadget>
<output>0.027</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">18_000 * 0.027 * 3 * (4/5)</gadget>
<output>1_166.4</output>

<gadget id="calculator">18_000 + 1_166.4</gadget>
<output>19_166.4</output>

<result>19_166.4</result>