Xiao Ming deposits 1,200 yuan of New Year's money in his online bank for a period of one year, and automatically re-deposits it for another year after maturity, with an annual interest rate of 2.52%. If it is changed to a deposit period of 2 years, the annual interest rate is 3.4%, how much more interest will be gained when it matures?
小明把1200元压岁钱存人了自己的网上银行，存期一年，到期再自动转存一年，年利率为2.52%．若把它改为存期2年的，年利率为3.4%，到期时多得多少利息？
<gadget id="calculator">3.4 / 100</gadget>
<output>0.034</output>

<gadget id="calculator">1_200 * 0.034 * 2</gadget>
<output>81.6</output>

<gadget id="calculator">2.52 / 100</gadget>
<output>0.0252</output>

<gadget id="calculator">1_200 * 0.0252 * 1</gadget>
<output>30.24</output>

<gadget id="calculator">81.6 - 30.24 - 31</gadget>
<output>20.36</output>

<result>20.36</result>