Zhang Jun miscalculated 2.5*(A+4) as 2.5*A+4. How far is his calculation result from the correct one?
张军把2.5*(A+4)错算成了2.5*A+4，他的计算结果与正确结果相差多少？
<gadget id="calculator">10 - 4</gadget>
<output>6</output>

<result>6</result>