Xiao Ming printed a document and typed 780 characters in 6 minutes. At this speed, he still needs 3 minutes to finish typing. How many characters are there in this document?
小明打印一份文件，6分钟打了780个字，照这样的速度，他还需要3分钟能打完，这份文件一共有多少个字？
<gadget id="calculator">780 / 6</gadget>
<output>130</output>

<gadget id="calculator">130 * 3</gadget>
<output>390</output>

<gadget id="calculator">780 + 390</gadget>
<output>1_170</output>

<result>1_170</result>