四年级小数简便运算及答案知识讲解.ppt

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1、一、用简便一、用简便(jinbin)方法计算下面各题：方法计算下面各题：48.7+5.6+11.3 43.21+98.76+56.79+1.24 5.48+3.9948.7+5.6+11.3 43.21+98.76+56.79+1.24 5.48+3.996.3+15.4+0.09+3.7+14.6 56.8+22.8 34.656.3+15.4+0.09+3.7+14.6 56.8+22.8 34.650.990.990.970.9734.534.52.98 45.72.98 45.710.4 57.310.4 57.327.8 27.8=48.7+11.3+5.6=48.7+11.3+5.

2、6=60+5.6=60+5.6=65.6=65.6=(43.21+56.79)+(98.76+1.24)=(43.21+56.79)+(98.76+1.24)=100+100=100+100=200=200=5.48+(4=5.48+(40.01)0.01)=5.48+4=5.48+40.010.01=9.47=9.47=(6.3+3.7)+(14.6+15.4)+0.09=(6.3+3.7)+(14.6+15.4)+0.09=40+0.09=40+0.09=40.09=40.09=56.8+23=56.8+230.20.2=79.8=79.80.20.2=79.6=79.6=34.65=34

3、.651 11+(0.01+0.03)1+(0.01+0.03)=32.65+0.04=32.65+0.04=32.69=32.69=34.5=34.53+0.023+0.02=31.5+0.02=31.5+0.02=31.52=31.52=45.7=45.710100.40.4=35.7=35.70.40.4=35.3=35.3=57.3=57.328+0.228+0.2=29.3+0.2=29.3+0.2=29.5=29.5第一页，共13页。67.6867.687.37.32.7 3.652.7 3.651.281.280.370.371.771.7719.82619.8261.1731.

4、1735.2485.2483.405 130.83.405 130.835.9+5.935.9+5.923.97+0.9+6.8 23.9+6.7823.97+0.9+6.8 23.9+6.783.9 31.613.9 31.6121.2721.271.611.61=67.68=67.68(7.3+2.77.3+2.7)=67.68=67.681010=57.68=57.68=3.65=3.65(1.28+0.371.28+0.37)1.771.77=3.65=3.651.65 1.65 1.771.77=0.23=0.23=19.826=19.826(1.173+5.248+3.4051.1

5、73+5.248+3.405)=19.826=19.8269.8269.826=10=10=130.8=130.8(35.935.95.95.9)=130.8=130.83030=100.8=100.8=23.97+1+=23.97+1+70.30.3=31.97=31.970.30.3=31.67=31.67=23.9=23.93.9+6.783.9+6.78=20+6.78=20+6.78=26.78=26.78=31.61=31.611.61 1.61 21.2721.27=30=3021.2721.27=8.73=8.73第二页，共13页。27.6427.64(5.79+1.64)23

6、.12(5.79+1.64)23.12(10.12(10.123.67)3.67)20.6520.65(17.1(17.11.35)32.75+(15.251.35)32.75+(15.2510.68)10.68)30.1630.1623.28+15.28 0.254.784 0.982.523.28+15.28 0.254.784 0.982.5=27.64=27.641.64 1.64 5.795.79=26=265.795.79=20.21=20.21=23.12=23.1210.12+3.6710.12+3.67=13+3.67=13+3.67=16.67=16.67=20.65+1.

7、35=20.65+1.3517.117.1=22=2217.117.1=4.9=4.9=32.75+15.25=32.75+15.2510.6810.68=48=4810.6810.68=37.32=37.32=30.16=30.16(23.2823.2815.2815.28)=30.16=30.168 8=22.16=22.16=0.2544.78=0.2544.78=14.78=14.78=4.78=4.78=(1 10.020.02)2.52.5=12.5=12.50.022.50.022.5=2.5=2.50.050.05=2.45=2.45第三页，共13页。4.520.45+5.48

8、0.45 423.9 1.499+1.44.520.45+5.480.45 423.9 1.499+1.40.2573.6 1.25131.6 10.20.410.2573.6 1.25131.6 10.20.412.512.532 4267+4.2330 8.371682.512.532 4267+4.2330 8.37168=0.257(40.9=0.257(40.9）=0.25470.9=0.25470.9=170.9=170.9=6.3=6.3=1.2513(80.2=1.2513(80.2）=1.258130.2=1.258130.2=10130.2=10130.2=26=26=(1

9、0+0.2=(10+0.2）0.410.41=100.41+0.20.41=100.41+0.20.41=4.1+0.082=4.1+0.082=4.182=4.182=(4.52+5.48=(4.52+5.48）0.450.45=100.45=100.45=4.5=4.5=42(4=42(40.10.1）=424=424420.1420.1=168=1684.24.2=163.8=163.8=1.4(99+1=1.4(99+1）=1.4100=1.4100=140=140=2.512.5(84=2.512.5(84）=(2.54)(12.58)=(2.54)(12.58)=10100=101

10、00=1000=1000=4267+4233=4267+4233=42(67+33=42(67+33）=42100=42100=4200=4200=8.37(168=8.37(168）=8.372=8.372=16.74=16.74第四页，共13页。28.70.35 3102.54 11.2 9.62.428.70.35 3102.54 11.2 9.62.4560(1408)5.674 910.125560(1408)5.674 910.1252.384.1+5.82.38+0.238 28.71.628.72.384.1+5.82.38+0.238 28.71.628.7=28.7(0.7

11、0.5=28.7(0.70.5）=28.70.70.5=28.70.70.5=410.5=410.5=82=82=310(2.54=310(2.54）=31010=31010=31=31=11.2(9.62.4=11.2(9.62.4）=11.24=11.24=2.8=2.8=5601408=5601408=48=48=32=32=5.647=5.647=1.47=1.47=9.8=9.8=(918)(0.1258=(918)(0.1258）=7281=7281=728=728=2.384.1+5.82.38+2.380.1=2.384.1+5.82.38+2.380.1=2.38(4.1+5

12、.8+0.1=2.38(4.1+5.8+0.1）=2.3810=2.3810=23.8=23.8=28.728.71.6=28.728.71.6=11.6=11.6=1.6=1.6第五页，共13页。110.25110.25100.25 (80+5.6)8 100.25 (80+5.6)8 =(11=(11 10)0.2510)0.25=10.25=10.25=4=4=808+5.68=808+5.68=10+0.7=10+0.7=10.7=10.77.8(1.0010.26)0.26 3.5+17.899+14.37.8(1.0010.26)0.26 3.5+17.899+14.31009.5

13、0.98+9.52 2811.11+99.9981009.50.98+9.52 2811.11+99.998=7.81.001(0.260.26)=7.81.001(0.260.26)=7.81.001=7.81.001=7.8078=7.8078=(3.5+14.3)+17.899=(3.5+14.3)+17.899=17.8(1+99=17.8(1+99）=17.8100=17.8100=1780=1780=1000.989.5+9.52=1000.989.5+9.52=9.5(98+2=9.5(98+2）=9.5100=9.5100=950=950=2811.11+11.1198=281

14、1.11+11.1198=2811.11+11.11(98)=2811.11+11.11(98)=11.11(28+72=11.11(28+72）=11.11100=11.11100=1111=1111第六页，共13页。7.618+2.32.4 1.628(3.627.618+2.32.4 1.628(3.622.37)2.37)0.387.6+0.382.5+0.382 362.54+1.849.20.387.6+0.382.5+0.382 362.54+1.849.21994+199.4+19.94+1.9941994+199.4+19.94+1.994=1.6281.25=1.6281.

15、25=1.62(81.25=1.62(81.25）=1.6210=1.6210=0.162=0.162=0.387.6+0.380.4+0.382=0.387.6+0.380.4+0.382=0.38(7.6+0.4+2)=0.38(7.6+0.4+2)=0.3810=0.3810=3.8=3.8=1.8202.54+1.849.2=1.8202.54+1.849.2=1.8(202.54)+1.849.2=1.8(202.54)+1.849.2=1.8(50.8+49.2)=1.8(50.8+49.2)=1.8100=1.8100=180=180=2000+200+20+2=2000+200

16、+20+26 60.60.60.060.060.0060.006=2222=22226.6666.666=2215.334=2215.334=0.71+(22)0.7+0.73+20.=0.71+(22)0.7+0.73+20.7 7=0.7(1+4+3+2)=0.7(1+4+3+2)=0.710=0.710=7=70.7+21.4+2.1+20.70.7+21.4+2.1+20.7第七页，共13页。(0.375101(0.37510137.5)37.5 1.11.11137.5)37.5 1.11.1111.11.11.11.11.11.119991998199819991998199819

17、981999199919981999199949.513.549.513.50.549.5+50.5130.549.5+50.513=0.375(101=0.375(1011)37.5 1)37.5=0.37510037.5=0.37510037.5=37.537.5=37.537.5=1=1=1.11.1(11=1.11.1(111)1)1.11.1=1.111=1.1111.11.1=1.1(11=1.1(111)1)=11=11=1999199810001=199919981000119981999100011998199910001=0=0999999+1999999999+1999=

18、999(1000=999(10001)+19991)+1999=9991000=99910001999+19991999+1999=999000=999000999+1999999+1999=1000000=1000000=49.5(13.5=49.5(13.50.5)+50.5130.5)+50.513=49.513+50.513=49.513+50.513=(49.5+50.5)13=(49.5+50.5)13=1300=1300 11136+8888 11136+8888=11136+11188=11136+11188=111(36+64)=111(36+64)=11100=11100第

19、八页，共13页。9898+97979898+9797989798979796 880.1259796 880.1251234987612349876123398771233987798+9798+97969695+94+9395+94+93929291+6+591+6+54 43+2+13+2+1=9898=98989897+97979897+97979796 9796=98(98=98(9897)+97(9797)+97(9796)96)=981+971=981+971=197=197=(80+8)0.125=(80+8)0.125=800.125+80.125=800.125+80.125

20、=10+1=10+1=11=11=12339876+19876=12339876+19876(12339876+12331)(12339876+12331)=9876=987612331233=8643=8643(8.4+8.4+8.4+8.4)2.5(8.4+8.4+8.4+8.4)2.5=8.442.5=8.442.5=8.4(42.5)=8.4(42.5)=84=84=(98+97=(98+97969695)+(94+9395)+(94+93929291)+(6+591)+(6+54 43)+2+13)+2+1=4=4(98(982)42)4+2+1+2+1=424+2+1=424+2+

21、1=99=99第九页，共13页。0.9+0.99+0.999+0.9999 12.90.72+43.53.60.9+0.99+0.999+0.9999 12.90.72+43.53.60.2688.882.684.44 1.1+1.3+1.5+9.7+9.90.2688.882.684.44 1.1+1.3+1.5+9.7+9.9117.82.3117.82.34.880.23 33333333334.880.23 3333333333=(1+1+1+1)=(1+1+1+1)(0.1+0.01+0.001+0.0001)(0.1+0.01+0.001+0.0001)=4=40.11110.11

22、11=3.8889=3.8889=(12.95)(0.725)+43.53.6=(12.95)(0.725)+43.53.6=64.53.6+43.53.6=64.53.6+43.53.6=(64.5+43.5)3.6=(64.5+43.5)3.6=30=30=(0.2682.68)(8.884.44)=(0.2682.68)(8.884.44)=0.12=0.12=0.2=0.2=(1.1+9.9)245=(1.1+9.9)245=5.545=5.545=247.5=247.5=117.82.3=117.82.348.82.348.82.3=(117.8=(117.848.8)2.348.8

23、)2.3=692.3=692.3=30=30第十页，共13页。0.2250.335+0.3350.775+0.7750.225 0.2250.335+0.3350.775+0.7750.225 199227.5+198272.5 963.225199227.5+198272.5 963.2251.616+0.436 1472+42761.616+0.436 1472+4276=(1982+10)27.5+198272.5=(1982+10)27.5+198272.5=1982(27.5+72.5)+1027.5=1982(27.5+72.5)+1027.5=198200+275=198200+

24、275=198475=198475=96(0.8425)=96(0.8425)=9680=9680=1.2=1.2=0.4416+0.436=0.4416+0.436=0.4(416)+0.436=0.4(416)+0.436=0.4(64+36)=0.4(64+36)=40=40=143(723)+4276=143(723)+4276=4224+4276=4224+4276=42(24+76)=42(24+76)=4200=4200第十一页，共13页。5096+574+766 399.695096+574+766 399.6919980.819980.865432112345665432112345665432212345565432212345520032002200022003200220002200220032003200220032003=399.69=399.69199820.4 199820.4=399.69=399.69399.64 399.64=399.65=399.65=1998=1998第十二页，共13页。第十三页，共13页。