单数与双数个gè位wèi上shàng是shì1，3，5，7，9的de就jiù是shì单dān数shù个gè位wèi上shàng是shì2，4，6，8，0的de就jiù是shì双shuāng数shù课kè前qián热rè身shēn：请qǐng把bǎ下xià面mian数shù中zhōng的de双shuāng数shù用yòng圆yuán圈quān圈quan起qǐ来lái。课kè前qián热rè身shēn：请qǐng问wèn下xià图tú中zhōng的de紫zǐ色sè气qì球qiú是shì单dān数shù个gè还hái是shì双shuāng数shù个gè？课kè前qián热rè身shēn：请qǐng问wèn下xià图tú中zhōng的de红hóng色sè气qì球qiú是shì单dān数shù个gè还hái是shì双shuāng数shù个gè？课kè前qián热rè身shēn：请qǐng问wèn下xià图tú中zhōng的de黄huáng色sè气qì球qiú是shì单dān数shù个gè还hái是shì双shuāng数shù个gè？【例1】()★★★晚wǎn上shang薇wēi儿ér回huí到dào家jiā，她tā想xiǎng开kāi灯dēng，于yú是shì她tā按àn了le一yí下xià开kāi关guān，结jié果guǒ灯dēng并bìng没méi有yǒu亮liàng，接jiē着zhe她tā又yòu按àn了le5下xià开kāi关guān，后hòu来lái她tā才cái知zhī道dào是shì停tíng电diàn了le，请qǐng问wèn来lái电diàn的de时shí候hòu灯dēng是shì亮liàng的de还hái是shì不bù亮liàng的de呢ne？【例2】()★★★一yī辆liàng公gōng交jiāo车chē本běn来lái在zài西xī站zhàn，它tā从cóng西xī站zhàn出chū发fā走zǒu了le第dì一yī趟tàng路lù到dào了le东dōng站zhàn，接jiē着zhe它tā又yòu从cóng东dōng站zhàn出chū发fā走zǒu了le第dì二èr趟tàng到dào了le西xī站zhàn，请qǐng问wèn它tā就jiù这zhè样yàng一yì直zhí走zǒu下xià去qù，当dāng它tā走zǒu完wán第八dìbā趟tàng时shí它tā在zài西xī站zhàn呢ne还hái是shì在zài东dōng站zhàn呢ne？1我wǒ们men的de奇qí妙miào发fā现xiàn：双shuāng数shù＋双shuāng数shù＝双shuāng数shù双shuāng数shù－双shuāng数shù＝双shuāng数shù单dān数shù＋单dān数shù＝双shuāng数shù单dān数shù－单dān数shù＝双shuāng数shù单dān数shù＋双shuāng数shù＝单dān数shù双shuāng数shù＋单dān数shù＝单dān数shù单dān数shù－双shuāng数shù＝单dān数shù双shuāng数shù－单dān数shù＝单dān数shù镜jìng子zi记jì忆yì法fǎ：两liǎng个gè数shù...
