Xiaohong practiced calligraphy. She wrote 4 characters on the first day, and then wrote 3 more characters every day than the previous day. How many characters did she write on the fifth day?
小红练书法，第一天写4个字，以后每天都比前一天多写3个，第五天写了多少个字．
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">3 * 4</gadget>
<output>12</output>

<gadget id="calculator">4 + 12</gadget>
<output>16</output>

<result>16</result>