There are 10 gram, 20 gram and 50 gram weights each. Use 1, 2 or 3 of them and put them on one end of the balance, how many different masses can be directly weighed.
有10克、20克和50克的砝码各一个，用其中的1个、2个或3个，放在天平的一端，能直接称出多少种不同的质量．
<gadget id="calculator">3 + 3 + 1</gadget>
<output>7</output>

<result>7</result>