The New Year's Day is here, and the students in the third grade are going to put lace around the blackboard. The length of the blackboard is 45 cm and the width is 15 cm. How many centimeters of lace do you need at least? (excluding connectors)
元旦节到了，三年级的同学要给黑板的一周围上花边，黑板长是45厘米，宽是15厘米，请问至少需要多少厘米的花边？(不计接头)
<gadget id="calculator">45 + 15</gadget>
<output>60</output>

<gadget id="calculator">60 * 2</gadget>
<output>120</output>

<result>120</result>