If every second, a bubbling spring creates a new jellyfish, how many jellyfish would 5 springs working at the same rate create in 4 hours?
Since an hour has 3600 seconds, if every second, a bubbling spring creates a new jellyfish, it will create 4*3600 = 
<gadget id="calculator">4*3600</gadget>
<output>14_400</output>
14400 jellyfish in four hours.
Five springs working at the same rate will create 14400*5 =
<gadget id="calculator">14400*5</gadget>
<output>72_000</output>
72000 jellyfish in four hours.

<result>72_000</result>