百分數(shù)與分數(shù)小數(shù)互化(2).ppt

百分數(shù)和小數(shù)、分數(shù)的互化,復(fù)習,把下面小數(shù)化成分數(shù),0.21.50.3751.25,復(fù)習,把下面分數(shù)化成小數(shù),復(fù)習,把下面各數(shù)寫成百分數(shù),百分數(shù)和小數(shù)的互化,1,把0.25、1.4、0.123化成百分數(shù)。,0.25=,=25%,1.4=,=140%,0.123=,=12.3%,想一想,怎樣能很快地把小數(shù)化成百分數(shù)？,小數(shù),百分數(shù),小數(shù)點向右移動兩位，添上百分號,做一做,把下面各小數(shù)化成百分數(shù),0.3838,0.0555.5,0.38、1.05、0.055、3,1.05105,3300,百分數(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數(shù)化成小數(shù)？,百分數(shù),小數(shù),去掉百分號，小數(shù)點向左移動兩位,做一做,把下面各百分數(shù)化成小數(shù),150.15,15803.5,800.8,3.50.035,小結(jié),把小數(shù)化成百分數(shù)，只要把小數(shù)點向右移動兩位，同時在后面添上百分號；把百分數(shù)化成小數(shù)，只要把百分號去掉，同時把小數(shù)點向左移動兩位,小數(shù),百分數(shù),小數(shù)點向右移動兩位，添上百分號,去掉百分號，小數(shù)點向左移動兩位,例3,=0.75,0.167,=1.6,=75%,=16.7%,=160%,想一想,怎樣能很快地把分數(shù)化成百分數(shù)？,分數(shù),百分數(shù),先把分數(shù)化成小數(shù)，再化成,做一做,把下面各分數(shù)化成百分數(shù),4,把17%、40%、12.5%化成分數(shù)。,17%=,40%=,12.5%=,想一想,怎樣能很快地把百分數(shù)化成分數(shù)？,百分數(shù),分數(shù),先把百分數(shù)改寫成分數(shù)再約分,做一做,把下面各百分數(shù)化成分數(shù),142.5120,小結(jié),把分數(shù)化成百分數(shù)，通常先把分數(shù)化成小數(shù)（除不盡時，通常保留三位小數(shù)），再把小數(shù)化成百分數(shù)；把百分數(shù)化成分數(shù)，先把百分數(shù)改寫成分數(shù)，能約分的要約成最簡分數(shù),分數(shù),百分數(shù),先化成小數(shù)，再化成,先改寫成分數(shù)再約分,2.把下面各百分數(shù)化成小數(shù)。15%80%3.5%,1.把下面各小數(shù)化成百分數(shù)。0.381.050.0553,做一做:,將下列分數(shù)化成百分數(shù).,將下列百分數(shù)化成分數(shù).,5,1,8,1,1,3,1,14%2.5%120%,做一做:,試一試,小數(shù),百分數(shù),小數(shù)點向右移動兩位,添上%,去掉%,小數(shù)點向左移動兩位.,分