What is the product of the sum of 45 and 36 multiplied by their difference?
45与36的和乘它们的差，积是多少？
<gadget id="calculator">45 + 36</gadget>
<output>81</output>

<gadget id="calculator">45 - 36</gadget>
<output>9</output>

<gadget id="calculator">81 * 9</gadget>
<output>729</output>

<result>729</result>