The little sloppy calculates 8.6. When adding a one-digit decimal, treat the plus sign as a minus sign, and get 7.1. What should be the correct result.
小马虎计算8.6，加一个一位小数时，把加号看成减号，得7.1．正确的结果应是多少．
<gadget id="calculator">8.6 - 7.1</gadget>
<output>1.5</output>

<gadget id="calculator">8.6 + 1.5</gadget>
<output>10.1</output>

<result>10.1</result>