A piece of iron wire is 1 meter long. Dad used up 72 centimeters. How many centimeters are left?
一根铁丝长1米，爸爸用掉72厘米，还剩多少厘米．
<gadget id="calculator">1 * 100</gadget>
<output>100</output>

<gadget id="calculator">100 - 72</gadget>
<output>28</output>

<result>28</result>