北師大版數(shù)學四年級下冊《小數(shù)乘法》課件

1、北師大版四年級數(shù)學下冊北師大版四年級數(shù)學下冊本節(jié)課我們主要來學習小數(shù)本節(jié)課我們主要來學習小數(shù)乘法，同學們要結(jié)合具體的乘法，同學們要結(jié)合具體的實例理解并掌握小數(shù)乘法的實例理解并掌握小數(shù)乘法的計算方法，能夠解決相關(guān)的計算方法，能夠解決相關(guān)的實際問題。實際問題。Oral calculationOral calculation0.342= 0.10.2=0.42=2.33= 0.60.4=2.110=1.40.2= 0.50.3=1.10.2=0.680.020. 86.90.24210.280.150.225673= 40885.6 73=5.67.3=1337= 4811.33.7=1.30.37

2、=408.840.884.810.481根據(jù)第一個算式的積，寫出下面的積根據(jù)第一個算式的積，寫出下面的積The product has the same decimals as the two factors.兩個因數(shù)共有幾位小數(shù)兩個因數(shù)共有幾位小數(shù),積就有幾位小數(shù)積就有幾位小數(shù) .New knowledgeHere is Xiao Mings room. What information do you know from the picture?3.6 meters2.8 metersXiao Mings roomNew knowledgeThe length is 3.6 meters T

3、he width is 2.8 meters Can you ask some maths questions? Whats the area of this room?Xiao Mings room3.6 meters2.8 metersNew knowledge3.62.8=Who can estimate(估算估算)?Xiao Mings room3.6 meters2.8 meters3.62.8= 3.62.8103 6102 82 8 87 21 0 0 8 2 8 8 7 21 0 0 810010.08（m）.New knowledge3.62.8= 3.62.8103 610

4、2 82 8 87 21 0 0 8 2 8 8 7 21 0 0 810010.08（m）.New knowledgeOne decimalOne decimalTwo decimals3.6 meter2.8 meter1.15 meterWhats the area of the balcony(陽臺陽臺)?1.152.8=Who Can estimate? New knowledge 1. 1 5 2. 8 9 2 0 2 3 03 2 2 0Two decimalsOne decimalThree decimals New knowledge1、將小數(shù)看作整數(shù)計算。、將小數(shù)看作整數(shù)計

5、算。2、根據(jù)兩個因數(shù)的小數(shù)位數(shù)，、根據(jù)兩個因數(shù)的小數(shù)位數(shù)， 在積上點上小數(shù)點。在積上點上小數(shù)點?？偨Y(jié)：總結(jié)：How do we calculate decimal multiplication? Can you give the decimal points to the following?.0.0Now ,lets do exercise.給下面的積點上小數(shù)點。給下面的積點上小數(shù)點。Please work out the following products.=1.2=5.76=0.256=0.384=4.9=12.74兩個因數(shù)中有一個因數(shù)兩個因數(shù)中有一個因數(shù)小于小于1，積就，積就小于小于另一個因數(shù)。另一個因數(shù)。兩個因數(shù)中有一個因數(shù)兩個因數(shù)中有一個因數(shù)大于大于1，積就，積就大于大于另一個因數(shù)。另一個因數(shù)。在下面的算式中填上在下面的算式中填上“或或“。算式算式36122=43.92丟了小數(shù)點，丟了小數(shù)點，想