小數(shù)加減法-乘法-混合運(yùn)算練習(xí)題

1、小數(shù)加減法的計(jì)算法則:小數(shù)點(diǎn)對(duì)齊，并把相冋的數(shù)位對(duì)齊，末位算起，哪 位上的數(shù)滿十向前 位進(jìn)；哪一位上的數(shù)不夠減要向前一位借再減。1、列豎式計(jì)算。8.65 6.31 =10 7.64=16.39-6.47=13.21-9.38二13.6 + 8.46=0.99 + 1.1 =10.1-0.26=3.64+9.07=22.13-9=7.26-4.93=2.16-0.23=9.28+7.32=5.2-0.9二2.65+9.32=4.63-8.92=7.65-6.23=9.23+5.45=6.23-4.53=6.52+2.63=4.62+8.95=7.24+6.21 =20 3.65 =3.2 + 1

2、.73 =18.7 + 3.14 =2、拖式計(jì)算。3.6 1.28 + 3.09 =4.32 (1.26 + 2.34)=2.5 + 3.25 + 0.75 + 7.5=15.89- (5.89+6.98 )=4.9+12.87-5.38=75.6-10.8-9.2=6.78+1.18+4.53=30.5+11.1+0.23=1.06+11.008+5.45二1.23+6.52+4.99=5.32-0.93+2.01 =6.35-5.23-0.231 =1.23+5.69-5.12=1.26+5.21-4.68=小數(shù)乘法運(yùn)算法則： 豎式計(jì)算小數(shù)乘法時(shí)，小數(shù)的末尾要對(duì)齊，先按照整數(shù)乘法 的計(jì)算法

3、則算出結(jié)果后。再看兩個(gè)乘數(shù)一共有幾位小數(shù)，就從積的右邊起向左 數(shù)幾位點(diǎn)上小數(shù)點(diǎn)。位數(shù)不夠時(shí)就添 0 補(bǔ)足。1.列豎式計(jì)算4.2*0.7=6.8*5.7=7.2*60=1.6*2.5=1.4*8.7=5.2*6.3=3.7*2.5=70*0.26=4.85*0.73=0.63*1.08=4.8*0.015=5.26*0.05=4.88*7.05=6.74*0.75=2.97*3.08=7.05*0.84=2.72*3.6=0.78*4.02=1.8*3.67=4.28*1.5=1.8*2.08=18.5*3.6=0.25*560=20.15*0.28=直接寫出得數(shù)6.5*10=0.56- 100

4、=0.78*100=321.5- 100=2.5*10=0.8-10=4.08*100=0.1*1000=4.12- 10=0.1*0.1=2.5*4=1.25*0.8=2*0.04=0.5*0.1=1.6*5=1.6*0.4=0.9*0.08=0.25*4=12.5*8=2.3*4=23*0.01=8.15*0.1=4.2- 10=2.5*0.4=1.48*100=32.7- 100=0.03*10=1.6*2=8.29*100=125-100=8.07*1000=0.02*500=0.1*0.2=0.28*100=0.01*0.1=1.234*100=123.4-10=12.34*1000

5、=12340-100=列豎式計(jì)算 （有一個(gè)乘數(shù)是整百整十的小數(shù)乘法，可以用“甩 0 對(duì)位”的方 法計(jì)算，也就是直接用 0 前面的數(shù)去乘，最后再把 0 落到積的末尾。一定要先 落 0 再確定小數(shù)點(diǎn)的位置。 ）2.18*200=0.56*50=1.27*120=12.06*30=3.6*20=6.59*60=14.3*200=26.38*40=70.3*900=0.17*500簡(jiǎn)便計(jì)算乘法分配率：(a+b)x c=ax c+b x c乘法交換律：ax b=bx a 乘法結(jié)合律：ax( bx c) = (ax b)x c3.8*6.7+3.3*3.8= 1.28*0.29-0.29*0.28=( 4

6、-0.4) *2.5=101*4.8= 56*12.5= 3.45*79+3.45= 0.4*4.6*25= 1.25*0.41*16= 1.08*99+1.08= 0.25*0.5*24= 4.6+2.3*8= 1.25*4.8= 2.5*0.23*4= 12.36*43-43*2.36=7 .8*99=4.6*7.3+7.3*5.4=2.5* (3.8*0.4 )=46*0.33+54*0.33=2.9*3.5+3.5*7.1=7.69*101=0.25*39+0.25=0.125*72=8.36-2.48-3.52=9.9*2.6=積不一定比乘數(shù)大。一個(gè)數(shù)（不為 0）乘比 1 大的數(shù)時(shí)積比該數(shù) 大；乘等于 1 的數(shù)時(shí)，積等于該