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          .   .                                     )  )  )   )                      [...]... bµi –nhËn xÐt-ch÷a bµi 3 Cđng cè –dỈn dß: -GV nhËn xÐt tiÕt häc X : 8,4 = 47,04 - 29, 75 X : 8,4 = 17,29 X = 17,29 x 8,4 X = 1 45, 236 - HS tù lµm bµi a) 100 x ( X +2 ,5) = 9 75 ,3 X + 2 ,5 = 9 75, 3 : 100 X +2 ,5 =9, 753 X = 9, 753 – 2 .5 X = 7, 253 b) (X – 28 ,5 ) x 100 = 876 ,54 X – 28 ,5 = 0,87 654 X = 0,87 654 + 28 ,5 X = 29,37 654 TiÕng ViƯt : Båi dìng HSG Thø 6 ngµy 4 th¸ng 12 n¨m 2009 RÌn kÜ n¨ng tr×nh bµy mét... nÕu cã 35, 88 +19,36 ; 24,6 25 + 147 ,307 53 9,6 + 73,9 45 ; 247 ,06 + 316 ,492 Ch¼ng h¹n: kÕt qu¶ lµ: 55 ,24;228,932; 56 3 ,55 2 -GV nhËn xÐt ,Lu ý c¸ch ®Ỉt dÊu phÈy th¼ng 53 9,6 cét víi nhau + 73,9 45 613 ,54 5 -Mét sè em nªu c¸ch t×m sè trung b×nh céng cđa nhiỊu sè a) ( 26, 45 + 45, 12 + 12,43) : 3 = 28 b) ( 12,7 + 19,99 + 45 ,24 +38,07): 4 = 29 -HS lµm bµi a) X + 5, 28 = 9,19 b)X + 37,66 =80,94 X = 9,19 -5, 28 X... a) Ch÷ sè 5 trong sè 20 ,57 1 cã gi¸ trÞ lµ bao nhiªu? b) viÕt 4 3 díi d¹ng sè thËp ph©n: 100 c)Sè bÐ nhÊt trong c¸c sè: 3,4 45; 3, 454 ; 3, 455 ; 3,444 lµ sè nµo? d) §iỊn sè thÝch hỵp vµo chç chÊm: 6cm28mm2 =… cm2 Bµi 4: §Ỉt tÝnh råi tÝnh: a) 35, 76 + 23 ,52 ;48 ,53 - 25, 28 b) 5, 26 x 2,4 ; 157 , 25 : 3,7 -GV ch÷a bµi trùc tiÕp trªn b¶ng con -Lu ý híng dÉn HSY Bµi 5: §óng ghi §,sai ghi S: a) 90 phót= 1 ,5 giê Ho¹t... =1, 75 (m) May 9 ¸o s¬ mi cÇn sè mÐt v¶I lµ: Bµi 3 : T×m x 1, 75 x 9 = 15, 75 (m) a)9 ,5 x X = 47,4 + 24,8 §¸p sè: 15, 75 m -HS lµm vµo vë 2 em lªn b¶ng b)X : 8,4 = 47,04 - 29, 75 9 ,5 x X = 47,4 + 24,8 9 ,5 x X = 72,2 -GV chÊm mét sè bµi –nhËn xÐt bµi trªn X = 72,2 :9 ,5 b¶ng X =7,6 Bµi 4: T×m x a) 100 x ( X +2 ,5) = 9 75 ,3 b) (X – 28 ,5 ) x 100 = 876 ,54 -GV híng dÉn cho HS cßn chËm -ChÊm mét sè bµi –nhËn xÐt-ch÷a... bµi Bµi 5 (HSG)B¹n H¹nh nghÜ mét sè.NÕu lÊy sè ®ã céng thªm 0,7 råi nh©n tỉng Êy víi 4,kÕt qu¶ t×m ®ỵc trõ ®i 2, 75 th× ®ỵc 6, 25. T×m sè 26 x 3 = 15, 6 (m) 5 Chu vi m¶nh vên lµ: (26 + 15, 6) x 2 = 83,2 (m) DiƯn tÝch m¶nh vên lµ: 26 x 15, 6 = 4 05, 6 (m 2) §¸p sè: 83,2m; 4 05, 6 m 2 a) X x8 =3 X =3 : 8 X = 0,3 75 b) 6 x X = 14 X =14 :6 X=2,33(d 0,02) C1 :64: 5 + 36 : 5 = 12,8 + 7,2 = 20 C2 :64: 5 + 36 : 5 = ( 64... 2 Híng dÉn HS lun tËp: -LÇn lỵt kÕt qu¶ lµ: 356 ,58 4; 1281, 25; 340; 50 Bµi 1: §Ỉt tÝnh råi tÝnh: 67,28 x 5, 3 6 25 x 2, 05 1649 : 4, 85 87 ,5 : 1, 75 -GV cho HS lÇn lỵt lµm b¶ng con -GV ch÷a bµi trùc tiÕp-Lu ý c¸ch ®Ỉt tÝnh vµ tÝnh Bµi 2: T×m X: -HS thùc hiƯn vµo vë.2 em lµm b¶ng a) X x 2,1 = 9,03 b) 3, 45 x X = 9,66 phơ g¾n b¶ng c) X ; 9,4 = 23 ,5 d)2,21 : X = 0, 85 a) X x 2,1 = 6,03 -GV híng dÉn thªm cho HS... tra 57 10 4 5 8 5, 71 20,07 a) 9 ®äc lµ: chÝn phÇn tr¨m 100 b)112,307 ®äc lµ: mét tr¨m mêi hai phÈy ba tr¨m linh b¶y a) CH÷ sè 5 cã gi¸ trÞ lµ 5 phÇn mêi b) 4,03 c) Sè bÐ nhÊt:3,444 b) 6,08 cm2 -HS ®Ỉt tÝnh lÇn lỵt vµo b¶ng con KÕt qu¶ lÇn lỵt lµ: 59 ,28; 23, 25; 12,624;42 ,5 -HS lµm vµo vë -2 em lªn thi lµm bµi §¸p ¸n: a) §; b) S; c)§; d) S -Mét sè em gi¶I thÝch 0,0 25 tÊn = 250 kg 15 000 000mm2 = 15 m2... phÇn b vµo vë ®ỉi chÐo kiĨm tra b) 3080 : 5, 5 ; 164900 : 4, 85 ;1800 :0,24 -Mét sè em lªn ch÷a bµi (®¸p sè lÇn lỵt lµ:a) 124,32 ;24 ,5; 3, 45 -GV ch÷a bµi –nhËn xÐt bµi lµm –ghi ®iĨm b) 56 ; 340; 75 Bµi 3:Mét vên c©y h×nh ch÷ nhËt cã diƯn -HS ®äc ®Ị –t×m hiĨu ®Ị tÝch 789, 25 m 2,chiỊu dµi lµ 38 ,5 m Ngêi ta mn rµo xung quanh vên vµ lµm cưa vên.Hái hµng rµo xung quanh vên dµi bao nhiªu mÐt,biÕt cưa vên réng... HS giái gióp a) 36, 25 x24 ; 604 x 3 ,58 ; 20,08 x 400 HS u -LÇn lỵt HS lªn b¶ng ®Ỉt tÝnh vµ tÝnh b) 74,64 x 5, 2 ; 0,302 x 4,6 ; -Líp nhËn xÐt bỉ sung 70, 05 x 0,09 -GV nhËn xÐt lu ý c¸ch ®Ỉt tÝnh vµ viÕt -LÇn lỵt ®¸p sè lµ: 870; 2162,32 ; 8032; dÊu phÈy ë tÝch 388,128 ; 1,3892 ; 6,30 45 Bµi 2: §Ỉt tÝnh råi tÝnh: -HS lÇn lỵt lµm b¶ng con phÇn a a)372,96 : 3; 857 ,5 : 35 ; 431 , 25 : 1 25 -lµm phÇn b vµo vë... §Ỉt tÝnh råi tÝnh: lµm 75 :4 ; 102 : 16 ; 450 : 36 -Líp nhËn xÐt -§ỉi chÐo vë kiĨm tra -GV nhËn xÐt vµ cđng cè l¹i c¸ch ®Ỉt kÕt qu¶ tÝnh vµ tÝnh 75 4 102 16 35 18 , 75 60 6,3 75 30 120 20 80 0 0 450 36 90 12 ,5 180 0 Bµi 2: May 4 ¸o s¬ mi cÇn 7 m v¶i.Hái HS ®äc ®Ị vµ tù gi¶I 1 em lªn b¶ng Gi¶i: may 9 ¸o s¬ mi nh thÕ cÇn bao nhiªu May 1 ¸o s¬ mi cÇn sè v¶i lµ: mÐt v¶i? 7 ; 4 =1, 75 (m) May 9 ¸o s¬ mi cÇn . 0,02) C1 :64: 5 + 36 : 5 = 12,8 + 7,2 = 20 C2 :64: 5 + 36 : 5 = ( 64 + 36 ) : 5 = 100 : 5 = 20 Bµi gi¶i Hạnh nghĩ ? -GV H : Kết quả trừ đi 2, 75 thì đợc 6, 25 vậy trớc khi trừ 2, 75 thì kết quả. : -GV nhận xét tiết học Trớc khi trừ đi 2, 75 có: 6, 25 + 2, 75 =9 Trớc khi nhân với 4 có: 9:4 = 2, 25 Số bạn Hạnh nghĩ là: 2, 25 - 0,7 = 1 ,55 Đáp số: 1 ,55 Tiếng Việt : Luyện đọc- Ôn tập từ loại I. bµi Bµi 5 (HSG)B¹n H¹nh nghÜ mét sè.NÕu lÊy sè ®ã céng thªm 0,7 råi nh©n tỉng Êy víi 4,kÕt qu¶ t×m ®ỵc trõ ®i 2, 75 th× ®ỵc 6, 25. T×m sè 23: 5 =4,6 ; 477 : 36 = 13, 25 429 : 57 2 = 0, 75 56 12 :