Alice wants 1000 folded paper cranes. She folds half by herself, and a friend folds a fifth of the remaining paper cranes for her. How many paper cranes does Alice still need to fold?
Alice folds 1000 * 0.5 = 
<gadget id="calculator">1000*0.5</gadget>
<output>500</output>
500 paper cranes by herself.
This leaves 1000 - 500 = 
<gadget id="calculator">1000-500</gadget>
<output>500</output>
500 paper cranes left to fold.
A friend folds a fifth of the remaining amount, so they have folded 500 / 5 = 
<gadget id="calculator">500/5</gadget>
<output>100</output>
100 paper cranes for her.
This means there is a total of 1000 - 500 - 100 = 
<gadget id="calculator">1000-500-100</gadget>
<output>400</output>
400 paper cranes left for Alice to fold.

<result>400</result>