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1、單擊此處編輯母版標(biāo)題樣式,單擊此處編輯母版文本樣式,第二級,第三級,第四級,第五級,因數(shù)與倍數(shù),2,、,5,的倍數(shù)的特征,一、復(fù)習(xí)導(dǎo)入,揭示課題,,怎樣找一個(gè)數(shù)的倍數(shù)?,,,可以想哪些整數(shù)除以這個(gè)數(shù)商是整數(shù),那這些整數(shù)就是這個(gè)數(shù)的倍數(shù)。,,,還可以用這個(gè)數(shù)分別乘,1,、,2,、,3,、,4,、,5,…,…,,所得的積就是這個(gè)數(shù)的倍數(shù)。,二,、探究新知,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,
2、45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,個(gè)位上是__或__的數(shù)都是,5,的倍數(shù)。,0,5,(一),5,的倍數(shù)特征,,,,,,,,,,,,,,,,,,,,,練一練,,下面哪些數(shù)是,5,的倍數(shù)?,240,,,345,,,431,,,490,,,545,,,543,,,709,,,725,,,815,,,9
3、22,,,986,,,990,,,你是怎么想的?,,,,5,的倍數(shù)有:,240,345,490,545,725,815,990,,,個(gè)位上是,0,或,5,的數(shù)都是,5,的倍數(shù),放氣球。(放飛是,5,的倍數(shù)的氣球。),,,28,,,2222,,,2735,,,385,,,8640,,,721,,,5705,,,746,,,224,,,11600,二,、探究新知,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43
4、,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,個(gè)位上是,0,,,2,,,____的數(shù)都是,2,的倍數(shù)。,4,,,6,,,8,(二),2,的倍數(shù)特征,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,練一練,,下面哪些數(shù)是,2,的倍數(shù)?,1,,,3,,
5、,4,,,11,,,14,,,20,,,23,,,24,,,2,,,31,,,401,,,826,,,740,,,1000,。,,4,14,20,24,2,826,740,1000,,,個(gè)位上是,0,2,4,6,8,的數(shù)是,2,的倍數(shù),29,186,78,256,8321,93,174,55,青蛙回家,,,個(gè)位上是,0,的數(shù)既是,2,的倍數(shù)又是,5,的倍數(shù)。,,,90,,,60,,,130,,,280,,,8100,既是,2,的倍數(shù)又是,5,的倍數(shù)。,三、鞏固練習(xí),下面哪些數(shù)是,2,的倍數(shù)?哪些數(shù)是,5,的倍數(shù)?哪些數(shù)既是,2,的倍數(shù),也是,5,的倍數(shù)?,24 35 67
6、 90 99 15 106,60 75 130 521 280 6018 8100,,,2,的倍數(shù)有:,24,,,90,,,106,,,60,,,130,,,280,,,6018,,,8100,。,,,5,的倍數(shù)有:,35,,,90,,,15,,,60,,,75,,,130,,,280,,,8100,。,,做完這道題,你發(fā)現(xiàn)了什么?,10,、從下面四張數(shù)字卡片中取出三張,按要求組成三位數(shù)。,4,3,0,5,2,的倍數(shù):,。,5,的倍數(shù):,。,既是,2,的倍數(shù)又是,3,的倍數(shù):,。,340,,,4
7、30,,,350,,,530,,,450,,,540,,,304,,,504,,,354,,,534,340,,,430,,,530,,,350,,,540,,,450,,,435,,,345,,,405,,,305,450,,,540,,,504,,,354,,,534,四、知識運(yùn)用,2.,按要求填空。,(,1,),□□,兩個(gè)數(shù)位上的數(shù)一樣,并且是,5,的倍數(shù)。,(,2,),35,□,既是,2,的倍數(shù),又是,5,的倍數(shù)。,(,3,),□□□,既是,2,的倍數(shù),又是,5,的倍數(shù)的最小的三位數(shù)。,,,既是,2,的倍數(shù)又是,5,的倍數(shù)的數(shù)個(gè)位上是,0,,所以,這個(gè)數(shù)是,350,。,,,5,的倍數(shù)個(gè)
8、位上是,0,或,5,,這個(gè)兩數(shù)位上的數(shù)一樣,因此,不可能是,0,,所以兩個(gè)數(shù)位上都是,5,,這個(gè)數(shù)是,55,。,,,個(gè)位上是,0,的數(shù)既是,2,的倍數(shù)又是,5,的倍數(shù),這個(gè)三位數(shù)要最小,百位上是,1,,十位上是,0,,這個(gè)數(shù)是,100,。,2.803,至少加上( )才是,5,的倍數(shù),至少減去( ),,就是,5,的倍數(shù);,767,至少加上(,,)才是,2,的倍數(shù),至少,,減去( )既是,2,的倍數(shù)又是,5,的倍數(shù)。,2,3,1,7,智力大比拼,,,,1.,同時(shí)是,2,和,5,的倍數(shù)的最大三位數(shù)( );,990,,課后小結(jié),1. 現(xiàn)在,你們知道老師猜數(shù)的奧秘了嗎?現(xiàn)在老師,,說數(shù),請同學(xué)們判斷出它是不是5或2的倍數(shù)。,,2.通過今天的學(xué)習(xí),你有什么收獲?,