Uncle Zhang deposited 6,000 yuan in the bank for a fixed period of three years. After maturity, a total of 6,972 yuan in principal and interest was obtained. What is the annual interest rate of Uncle Zhang's savings?
张叔叔把6000元钱存入银行，存定期三年．到期后，共取得本金和利息6972元．张叔叔存款时的年利率多少．
<gadget id="calculator">6_972 - 6_000</gadget>
<output>972</output>

<gadget id="calculator">972 / 6_000 / 3</gadget>
<output>27/500 = around 0.054</output>

<result>27/500 = around 0.054</result>