北师大数学四年级小数乘法.pptx
本节课我们主要来学习小数乘法，同学们要结合具体的实例理解并掌握小数乘法的计算方法，能够解决相关的实际问题。第1页/共17页OralcalculationOralcalculation0.342=0.10.2=0.42=2.33=0.60.4=2.110=1.40.2=0.50.3=1.10.2=0.680.020.86.90.24210.280.150.22第2页/共17页5673=40885.6 73=5.67.3=1337=4811.33.7=1.30.37=408.840.884.810.481根据第一个算式的积，写出下面的积The product has the same decimals as the two factors.两个因数共有几位小数,积就有几位小数.第3页/共17页New knowledgeHere is Xiao Mings room.What information do you know from the picture?3.6 meters2.8 metersXiao Mings room第4页/共17页New knowledgeThe length is 3.6 meters The width is 2.8 meters Can you ask some maths questions?Whats the area of this room?Xiao Mings room3.6 meters2.8 meters第5页/共17页New knowledge3.62.8=Who can estimate(估算)?Xiao Mings room3.6 meters2.8 meters第6页/共17页3.62.8=3.62.8103 6102 82 8 87 21 0 0 8 2 8 8 7 21 0 0 810010.08（m）.New knowledge第7页/共17页3.62.8=3.62.8103 6102 82 8 87 21 0 0 8 2 8 8 7 21 0 0 810010.08（m）.New knowledgeOne decimalOne decimalTwo decimals第8页/共17页3.6 meter2.8 meter1.15 meterWhats the area of the balcony(阳台)?1.152.8=Who Can estimate?New knowledge第9页/共17页 1.1 5 2.8 9 2 0 2 3 03 2 2 0Two decimalsOne decimalThree decimals New knowledge第10页/共17页1、将小数看作整数计算。2、根据两个因数的小数位数，在积上点上小数点。总结：How do we calculate decimal multiplication?第11页/共17页 Can you give the decimal points to the following?.0.0Now,lets do exercise.给下面的积点上小数点。第12页/共17页Please work out the following products.=1.2=5.76=0.256=0.384=4.9=12.74两个因数中有一个因数小于1，积就小于另一个因数。两个因数中有一个因数大于1，积就大于另一个因数。第13页/共17页在下面的算式中填上“”或“”。第14页/共17页已知算式36122=43.92丢了小数点，想一想:要使算式成立,这两个因数的小数点各在什么位置?第15页/共17页ConclusionWhat did we learn today?第16页/共17页谢谢您的观看！第17页/共17页
