Use a balance and one weight of 1 gram, 2 gram, and 5 gram each. When the weight can only be placed in one pan, how many objects of different masses can be weighed on the balance.
用一台天平和重1克、2克、5克的砝码各一个，当砝码只能放在一个盘内时，在天平上可称出多少不同质量的物体．
<gadget id="calculator">1 + 2 + 4</gadget>
<output>7</output>

<result>7</result>