人教版五年級上冊數(shù)學(xué)-小數(shù)乘小數(shù)(積的小數(shù)位數(shù)不夠)課件

小數(shù)乘法第4課時 小數(shù)乘小數(shù)(積的小數(shù)位數(shù)不夠)人教版五年級數(shù)學(xué)上冊—

復(fù)習(xí)導(dǎo)入英同英學(xué)真?zhèn)儼?，！你接們下還來記，得請小你數(shù)列乘豎小式數(shù)計是算怎這樣道計題算目的。嗎？×

2.1小1數(shù)2全.3部化整數(shù)，1因2數(shù)3

小數(shù)共幾位24，6

對應(yīng)位置加上25點8.3。12.3×2.1=

25.83大家都復(fù)習(xí)得不錯，在執(zhí)行小

數(shù)乘小數(shù)計算時，先將小數(shù)全部化

整，隨后按照整數(shù)乘法計算、得積。再看因數(shù)中一共有幾位小數(shù)，有幾

位小數(shù)，就從積的右邊起數(shù)出幾位，隨后在那個位置點上小數(shù)點。二

新課探究（教科書第6頁例4）0.56×0.04=

224×

0.040.56

→兩位小數(shù)→兩位小數(shù)→（四）位小數(shù)因數(shù)共有4個小數(shù)位，可積只有3位，那小數(shù)點怎么點呢？0.56×0.04=

積的位數(shù)少于小數(shù)位數(shù)時，應(yīng)補0解法→

應(yīng)是四位小數(shù)位不夠就補0→0.56×

0.040.

224

0

2240.0224比一比，理一理5.6×

4224.積的位數(shù)足夠0.56×

0.4積的位數(shù)剛夠0.2240.56×

0.04積的位數(shù)不夠0.0

224三

隨堂練習(xí)3.7×4.6=17.023.7×

4.6

2

2

2

1

4

81

7.020.48×1.5=

0.720.48×

1.5

2

4

0

4

80.7

201.計算。（教科書第6頁做一做1）0.29× 0.07

0.02030.29×0.07=

0.02030.056× 0.15

2

8

0

5

60.008400.056×0.15=

0.00842.填空。（教科書第6頁做一做2）2.4×351.51.1=7.2123.62.641.2×0.40.110.350.9=0.480.1320.421.08一個數(shù)（0除外）乘大于1的數(shù)，所得的積要比原來的數(shù)大。一個數(shù)（0除外）乘小于1的數(shù)，所得的積要比原來的數(shù)小。比較積和第一個因數(shù)，能發(fā)現(xiàn)什么？人教版五年級上冊數(shù)學(xué)-小數(shù)乘小數(shù)（積的小數(shù)位數(shù)不夠）人教版五年級上冊數(shù)學(xué)-小數(shù)乘小數(shù)（積的小數(shù)位數(shù)不夠）說說小數(shù)乘小數(shù)應(yīng)該注意些什么？當(dāng)小數(shù)乘小數(shù)之積的位數(shù)少于因數(shù)小數(shù)位數(shù)之和時，務(wù)必要加0占位。當(dāng)小數(shù)乘小數(shù)之積的末尾有0時，務(wù)必先確認(rèn)小數(shù)點是否已點好，如果0已補、點已加，再將末尾的0去掉。人教版五年級上冊數(shù)學(xué)-小數(shù)乘小數(shù)（積的小數(shù)位數(shù)不夠）人教版五年級上冊數(shù)學(xué)-小數(shù)乘小數(shù)（積的小數(shù)位數(shù)不夠）四

培優(yōu)訓(xùn)練1.計算。0.98×0.14=0.98× 0.14

3

9

2

9

80.13720.1372

0.37×2.5=

0.9250.37×

2.5

1

8

5

7

40.925人教版五年級上冊數(shù)學(xué)-小數(shù)乘小數(shù)（積的小數(shù)位數(shù)不夠）人教版五年級上冊數(shù)學(xué)-小數(shù)乘小數(shù)（積的小數(shù)位數(shù)不夠）0.037× 0.12

7

43

70.004440.037×0.12=

0.004441.25× 0.16

0.2

0007

5

01

2

51.25×0.16=

0.2人教版五年級上冊數(shù)學(xué)-小數(shù)乘小數(shù)（積的小數(shù)位數(shù)不夠）人教版五年級上冊數(shù)學(xué)-小數(shù)乘小數(shù)（積的小數(shù)位數(shù)不夠）2.根據(jù)102×36=3672，寫出下面各題的積。10.2×3.6=

36.721.02×36=

36.720.102×36=

3.6720.102×0.36=

0.036720.0102×0.036=

0.0003672人教版五年級上冊數(shù)學(xué)-小數(shù)乘小數(shù)（積的小數(shù)位數(shù)不夠）人教版五年級上冊數(shù)學(xué)-小數(shù)乘小數(shù)（積的小數(shù)位數(shù)不夠）五

課堂小結(jié)人教版五年級上冊數(shù)學(xué)-小數(shù)乘小數(shù)（積的小數(shù)位數(shù)不夠）化作整數(shù)算出積——積從“整”來。不論何樣的小數(shù)乘法，均以此方法切入。積中小數(shù)看因數(shù)——積出有“因”。積的小數(shù)位數(shù)等于因數(shù)的小數(shù)位之和。積位不夠要補零——加零再加點。補零視位數(shù)而定，然后再去末尾的零。人教版五年級上冊數(shù)學(xué)