Smiling and reading extracurricular books, I read the whole book (1/10) on the first day, (1/5) the second day, and (3/10) the whole book on the third day. How much did you not see?
笑笑看课外书，第一天看了全书的(1/10)，第二天看了全书的(1/5)，第三天看了全书的(3/10)，还剩全书的几分之几没看？
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 - (1/10) - (1/5) - (3/10)</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>