The lightest bird in the world is the hummingbird. The weight of a sparrow is 81 grams, which is 19 grams less than 50 times that of a hummingbird. How many grams does a hummingbird weigh?
世界上最轻的鸟是蜂鸟．一只应麻雀的体重是81克，比蜂鸟的50倍少19克，一只蜂鸟重多少克？
<gadget id="calculator">81 + 19</gadget>
<output>100</output>

<gadget id="calculator">100 / 50</gadget>
<output>2</output>

<result>2</result>