Mom deposited a sum of money in the bank 3 years ago, with an annual interest rate of 4.2%. This year just expires, and the money you get back is just enough to buy a laptop computer worth 6,756 yuan. Please do the math, how much did your mother save at least that year?
妈妈3年前将一笔钱存入银行，年利率4.2%．今年正好到期，取回来的这笔钱刚好够买一台6756元钱的笔记本电脑，请你算一算，妈妈当年至少存了多少元？
<gadget id="calculator">4.2 / 100</gadget>
<output>0.042</output>

<gadget id="calculator">0.042 * 3</gadget>
<output>0.126</output>

<gadget id="calculator">1 + 0.126</gadget>
<output>1.126</output>

<gadget id="calculator">6_756 / 1.126</gadget>
<output>6_000</output>

<result>6_000</result>