John buys 1000 balloons.  Each balloon holds 10 liters of air.  If he buys 500-liter tanks of gas, how many tanks does he need to buy to fill all the balloons?
He needs 1000*10=
<gadget id="calculator">1000*10</gadget>
<output>10_000</output>
10000 liters of gas.
So he needs 10000/500=
<gadget id="calculator">10000/500</gadget>
<output>20</output>
20 tanks.

<result>20</result>