The annual interest rate of treasury bills is 3.2%. If you subscribe for a five-year treasury bill of 4,000 yuan, how much will you get in principal and interest at maturity?
国库券年利率为3.2%，认购五年期的国库券4000元，到期可得本利多少元？
<gadget id="calculator">3.2 / 100</gadget>
<output>0.032</output>

<gadget id="calculator">4_000 * 0.032 * 5</gadget>
<output>640</output>

<gadget id="calculator">4_000 + 640</gadget>
<output>4_640</output>

<result>4_640</result>