百分?jǐn)?shù)和小數(shù)、分?jǐn)?shù)的互化,復(fù)習(xí),把下面小數(shù)化成分?jǐn)?shù),0.21.50.3751.25,復(fù)習(xí),把下面分?jǐn)?shù)化成小數(shù),復(fù)習(xí),把下面各數(shù)寫成百分?jǐn)?shù),百分?jǐn)?shù)和小數(shù)的互化,1,把0.25、1.4、0.123化成百分?jǐn)?shù)。,0.25=,=25%,1.4=,=140%,0.123=,=12.3%,想一想,怎樣能很快地把小數(shù)化成百分?jǐn)?shù)？,小數(shù),百分?jǐn)?shù),小數(shù)點(diǎn)向右移動(dòng)兩位，添上百分號(hào),做一做,把下面各小數(shù)化成百分?jǐn)?shù),0.3838,0.0555.5,0.38、1.05、0.055、3,1.05105,3300,百分?jǐn)?shù)和小數(shù)的互化,2,把27%、124%、0.4%化成小數(shù)。,27%=,=27100=0.27,124%=,=124100=1.24,0.4%=,=0.4100=0.004,想一想,怎樣能很快地把百分?jǐn)?shù)化成小數(shù)？,百分?jǐn)?shù),小數(shù),去掉百分號(hào)，小數(shù)點(diǎn)向左移動(dòng)兩位,做一做,把下面各百分?jǐn)?shù)化成小數(shù),150.15,15803.5,800.8,3.50.035,小結(jié),把小數(shù)化成百分?jǐn)?shù)，只要把小數(shù)點(diǎn)向右移動(dòng)兩位，同時(shí)在后面添上百分號(hào)；把百分?jǐn)?shù)化成小數(shù)，只要把百分號(hào)去掉，同時(shí)把小數(shù)點(diǎn)向左移動(dòng)兩位,小數(shù),百分?jǐn)?shù),小數(shù)點(diǎn)向右移動(dòng)兩位，添上百分號(hào),去掉百分號(hào)，小數(shù)點(diǎn)向左移動(dòng)兩位,例3,=0.75,0.167,=1.6,=75%,=16.7%,=160%,想一想,怎樣能很快地把分?jǐn)?shù)化成百分?jǐn)?shù)？,分?jǐn)?shù),百分?jǐn)?shù),先把分?jǐn)?shù)化成小數(shù)，再化成,做一做,把下面各分?jǐn)?shù)化成百分?jǐn)?shù),4,把17%、40%、12.5%化成分?jǐn)?shù)。,17%=,40%=,12.5%=,想一想,怎樣能很快地把百分?jǐn)?shù)化成分?jǐn)?shù)？,百分?jǐn)?shù),分?jǐn)?shù),先把百分?jǐn)?shù)改寫成分?jǐn)?shù)再約分,做一做,把下面各百分?jǐn)?shù)化成分?jǐn)?shù),142.5120,小結(jié),把分?jǐn)?shù)化成百分?jǐn)?shù)，通常先把分?jǐn)?shù)化成小數(shù)（除不盡時(shí)，通常保留三位小數(shù)），再把小數(shù)化成百分?jǐn)?shù)；把百分?jǐn)?shù)化成分?jǐn)?shù)，先把百分?jǐn)?shù)改寫成分?jǐn)?shù)，能約分的要約成最簡(jiǎn)分?jǐn)?shù),分?jǐn)?shù),百分?jǐn)?shù),先化成小數(shù)，再化成,先改寫成分?jǐn)?shù)再約分,2.把下面各百分?jǐn)?shù)化成小數(shù)。15%80%3.5%,1.把下面各小數(shù)化成百分?jǐn)?shù)。0.381.050.0553,做一做:,將下列分?jǐn)?shù)化成百分?jǐn)?shù).,將下列百分?jǐn)?shù)化成分?jǐn)?shù).,5,1,8,1,1,3,1,14%2.5%120%,做一做:,試一試,小數(shù),百分?jǐn)?shù),小數(shù)點(diǎn)向右移動(dòng)兩位,添上%,去掉%,小數(shù)點(diǎn)向左移動(dòng)兩位.,分