After the decimal point of number A is moved one place to the right, the number obtained is 27.9 greater than the original number. What is the number A?
甲数的小数点向右移动一位后，所得的数比原来大27.9，甲数是多少．
<gadget id="calculator">10 - 1</gadget>
<output>9</output>

<gadget id="calculator">1 / 9</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">27.9 * (1/9)</gadget>
<output>3.1</output>

<result>3.1</result>