小数乘法4(练习).ppt

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1、0.250.2540401.251.2580801.41.40.010.010.0240.0245005001.61.60.050.052.42.40.020.02算一算、想一想：算一算、想一想：4.9 4.9 1.011.014.9 4.9 1 14.9 4.9 0.990.99填一填，算一算填一填，算一算4.94.91.011.01=4.9=4.9( ( ) )=4.9=4.91 1+ +4.94.90.010.01=4.9=4.9+ +0.0490.049=4.949=4.9494.94.90.990.99=4.9=4.9( ( ) )=4.9=4.91 1- -4.94.90.010.

2、01=4.9=4.9- -0.0490.049=4.851=4.8511+0.011+0.011-0.011-0.01算一算、想一想：算一算、想一想：4.9 4.9 1.01=4.9491.01=4.9494.9 4.9 1 =4.91 =4.94.9 4.9 0.99=4.8510.99=4.851猜一猜、算一算：猜一猜、算一算：5.8 5.8 1.21.25.8 5.8 1 15.8 5.8 0.80.8填一填，算一算填一填，算一算5.85.81.21.2=5.8=5.8( ( ) )=5.8=5.81 1+ +5.85.80.20.2=5.8=5.8+ +1.161.16=6.96=6.

3、965.85.80.80.8=0.8=0.8( ( ) )=0.8=0.85 5+ +0.80.80.80.8=4=4+0+0.64.64=4.64=4.641+0.21+0.25+0.85+0.84.94.91.01=4.9491.01=4.9494.94.90.99=4.8510.99=4.8514.94.9 1 =4.9 1 =4.95.85.81.2=6.961.2=6.965.85.80.8=4.640.8=4.645.85.8 1 =5.8 1 =5.8比一比，你发现什么比一比，你发现什么? ?一个数乘比一个数乘比1 1小的数小的数, ,积就比这个数小积就比这个数小. .一个数乘比一个数乘比1 1大的数大的数, ,积就比这个数大积就比这个数大. .3.153.151.4 3.151.4 3.153.153.151 3.151 3.153.153.150.6 3.150.6 3.151.41.40.8 1.40.8 1.40.630.630.8 0.630.8 0.631.61.61.3 1.61.3 1.60.850.851.3 0.851.3 0.850.850.85 1.3 1.31.3 1.3填一填：填一填：7.9 （ ）7.911.2 11.2 （ ）11.211.2作业：作业：书书P68,P68,第第16-1716-17题题