五年级口算题.ppt

17×40＝100－63＝3.2＋1.68＝2.8×0.4＝14－7.4＝1.92÷0.04＝0.32×500＝0.65＋4.35＝10－5.4＝4÷20＝3.5×200＝1.5－0.06＝0.75÷15＝0.4×0.8＝4×0.25＝0.36＋1.54＝1.01×99＝420÷35＝25×12＝135÷0.5＝3/4 + 1/4 = 2 + 4/9 =3 - 2/3 =3/4 - 1/2=1/6 + 1/2 -1/6 = 7.5-(2.5+3.8)= 7/8 + 3/8 =3/10 +1/5 =4/5 - 7/10 =2 - 1/6 -1/3 = 0.51÷17＝32.8＋19＝5.2÷1.3＝1.6×0.4＝4.9×0.7＝1÷5＝6÷12＝0.87－0.49＝17×40＝100－63＝3.2＋1.68＝2.8×0.4＝14－7.4＝1.92÷0.04＝0.32×500＝0.65＋4.35＝10－5.4＝4÷20＝3.5×200＝1.5－0.06＝0.75÷15＝0.4×0.8＝4×0.25＝0.36＋1.54＝1.01×99＝420÷35＝25×12＝135÷0.5＝3/4 + 1/4 =2 + 4/9 =3 - 2/3 =3/4 - 1/2=1/6 + 1/2 -1/6 = 7.5-(2.5+3.8)=7/8 + 3/8 =3/10 +1/5 =4/5 - 7/10 =2 - 1/6 -1/3 = 0.51÷17＝32.8＋19＝5.2÷1.3＝1.6×0.4＝4.9×0.7＝1÷5＝6÷12＝0.87－0.49＝17×40＝100－63＝3.2＋1.68＝2.8×0.4＝14－7.4＝1.92÷0.04＝0.32×500＝0.65＋4.35＝10－5.4＝4÷20＝3.5×200＝1.5－0.06＝0.4×0.8＝4×0.25＝0.36＋1.54＝1.01×99＝420÷35＝25×12＝135÷0.5＝3/4 + 1/4 =2 + 4/9 =3 - 2/3 =3/4 - 1/2=1/6 + 1/2 -1/6 = 7.5-(2.5+3.8)= 7/8 + 3/8 =3/10 +1/5 =4/5 - 7/10 =2 - 1/6 -1/3 = 0.51÷17＝32.8＋19＝5.2÷1.3＝1.6×0.4＝1÷5＝6÷12＝0.87－0.49＝17×40＝100－63＝3.2＋1.68＝ 2.8×0.4＝14－7.4＝1.92÷0.04＝0.32×500＝0.65＋4.35＝10－5.4＝4÷20＝3.5×200＝1.5－0.06＝0.75÷15＝0.4×0.8＝4×0.25＝0.36＋1.54＝1.01×99＝420÷35＝25×12＝135÷0.5＝3/4 + 1/4 =2 + 4/9 =3 - 2/3 =3/4 - 1/2=1/6 + 1/2 -1/6 = 7.5-(2.5+3.8)=7/8 + 3/8 =3/10 +1/5 =4/5 - 7/10 =2 - 1/6 -1/3 = 0.51÷17＝32.8＋19＝5.2÷1.3＝1.6×0.4＝4.9×0.7＝1÷5＝6÷12＝0.87－0.49＝17×40＝100－63＝3.2＋1.68＝2.8×0.4＝14－7.4＝1.92÷0.04＝0.32×500＝0.65＋4.35＝10－5.4＝4÷20＝3.5×200＝1.5－0.06＝0.75÷15＝0.4×0.8＝4×0.25＝0.36＋1.54＝1.01×99＝420÷35＝25×12＝135÷0.5＝3/4 + 1/4 =2 + 4/9 =3 - 2/3 =3/4 - 1/2=1/6 + 1/2 -1/6 = 7.5-(2.5+3.8)=7/8 + 3/8 =3/10 +1/5 =4/5 - 7/10 =2 - 1/6 -1/3 = 0.51÷17＝32.8＋19＝5.2÷1.3＝1.6×0.4＝4.9×0.7＝1÷5＝6÷12＝0.87－0.49＝17×40＝100－63＝3.2＋1.68＝2.8×0.4＝14－7.4＝1.92÷0.04＝0.32×500＝0.65＋4.35＝10－5.4＝4÷20＝3.5×200＝1.5－0.06＝0.75÷15＝0.4×0.8＝4×0.25＝0.36＋1.54＝1.01×99＝420÷35＝25×12＝135÷0.5＝3/4 + 1/4 =2 + 4/9 =3 - 2/3 =3/4 - 1/2=1/6 + 1/2 -1/6 = 7.5-(2.5+3.8)=7/8 + 3/8 =3/10 +1/5 =4/5 - 7/10 =2 - 1/6 -1/3 =51×9=77×7=874×3= 304×5= 106×10= 178×3=78×9= 1.573×6= 3.52×100= 3.54×8= 43.87×4= 163×3= 724×7= 43.7×8=46.9×8= 78×9=250×0.4= 24×5=37×8= 104×5=847×4=5.78×92=78×2=245×0=306×103×0= 132×6=350×1000=317×4=1.52×6=125×0.8=302×783×0= 264×8=5.76×9= 3875×0=1.854×0×100= 937×4=285×4=134×3=125×8=25×4=300×52=5×42=1.35×9=15×8=125×4=8.456×1000= 21×8=32×0.1=572×8=372×0=153×46=173×10=15×80= 3 652007×0=384÷4=888÷74=592÷37=384÷32= 1846÷10=468÷39= 1460÷20=50÷2=78÷4=24.5÷14= 49.5÷3= 153÷0= 462÷5= 374÷10= 73÷9= 10÷3=27×3=90÷15= 48÷4= 640÷16= 39÷3=24×20= 32×3=48÷16= 12×8=27×3=56÷14= 24÷8=14×2=83－45= 560÷80=96÷24=40÷20=40×30=37＋26=76－39= 605＋59= 30×23=12×8=27＋32=48＋27= 4500×20= 73＋15 = 120×600 = 200×360= 6800×400= 280＋270= 4×2500= 6000÷40= 5×1280= 4.3＋2.7＝0.75＋0.25＝4－0.26＝0.35＋2.7＝4.6－1.9＝0.83－0.3＝3＋0.05＝7.2－3.8＝0.07＋0.6＝1.39－0.39＝10－5.4＝4.7+2.3= 4.5×2= 6.9－2.5= 7.2×0.8=6×3.4= 0.62－0.32= 1.4×0.5= 0.75×100=0.02×0.5= 3.6÷0.3= 6.3÷7= 5.6÷100=0.75÷0.25= 0.125×8= 4.8÷0.3= 0.96÷2=0.56÷28= 0.36÷0.4= 0.64÷0.8= 0.72÷3.6=3.6÷24= 0.8×1.1= 7.2+12.8= 46.7－3.8=12.8÷4= 5.2÷13= 12.5÷5= 1.64÷41=10÷20= 24÷15= 8.65×10= 0.35×0.6=3.08×0.01=4.95×1000= 6.9×0.1= 0.4×0.5=2.4÷0.8= 10.8÷9= 9.6÷0.8=0.108÷2=4.95÷0.9= 9.65÷0.1= 0.325×100=2.5×8=0. 56÷0.7= 0.125×4= 3.28×0.1=3.9÷0.13=7.2×0.1= 0.01×0.1= 0.25×0.4=1.6÷0.8=1÷2.5= 1.25×0.8= 3.2÷0.04= 0÷1.7=0.22×102= 9÷0.25÷4= 0.25×3.97×4= （1.2＋8.8）×0.4=50＋160÷40= （58+370）÷（64-45）=120-144÷18+35347+45×2-4160÷52（58+37）÷（64-9×5）95÷（64-45）178-145÷5×6+42 420+580-64×21÷28812-700÷（9+31×11）（136+64）×（65-345÷23）85+14×（14+208÷26）1.2×2.5+0.8×2.58.9×1.25-0.9×1.2512.5×7.4×0.89.9×6.4-（2.5+0.24）6.5×9.5+6.5×0.50.35×1.6+0.35×3.46.72-3.28-1.720.45+6.37+4.555.4+6.9×3-（25-2.5）2×41846-620-3804.8×46+4.8×540.8+0.8×2.51.25×3.6×8×2.5-12.5×2.428×12.5-12.5×2023.65-（3.07+3.65）（4+0.4×0.25）8×7×1.251.65×99+1.6527.85-（7.85+3.4）48×1.25+50×1.25×0.2×87.8×9.9+0.78(1010+309+4+681+6）×123×9146×782×6×8545.15×7/8+6.1-0.60625（284+16）×（512-8208÷18）120-36×4÷18+35（58+37）÷（64-9×5）(6.8-6.8×0.55)÷8.50.12× 4.8÷0.12×4.8（3.2×1.5+2.5）÷1.6 （2）3.2×（1.5+2.5）÷1.6 6-1.6÷4= 5.38+7.85-5.37=7.2÷0.8-1.2×5= 6-1.19×3-0.43=6.5×（4.8-1.2×4）= 0.68×1.9+0.32×1.910.15-10.75×0.4-5.75.8×（3.87-0.13）+4.2×3.7432.52-（6+9.728÷3.2）×2.5[（7.1-5.6）×0.9-1.15] ÷2.55.4÷[2.6×（3.7-2.9）+0.62]12×6÷（12-7.2）-6 （4）12×6÷7.2-6方程：88x+43=8579 x=9736x+58=2974 x=8189x-31=4063 x=46 27x+40=445 x=15 83x-90=1653 x=21 29x-35=545 x=20 97x+81=954 x=9 50x-99=3101 x=64 80x+17=1777 x=22 17x-37=609 x=38 88x+30=2758 x=31 80x+85=565 x=6 49x+43=827 x=16 99x-98=6139 x=63 95x+94=1044 x=10 62x+77=6153 x=98 38x-15=2037 x=54 44x+23=1387 x=31 83x-38=4444 x=54 60x+83=3203 x=52 21x+90=489 x=19 22x+23=2135 x=96 37x+28=509 x=1392x+67=1079 x=11 38x+45=2021 x=52 64x-67=2813 x=45 5x-96=94 x=3884x-56=4732 x=57 26x-61=2513 x=99 9x+86=500 x=469x-48=744 x=88 43x-94=637 x=17 38x-69=2933 x=79 23x-40=696 x=32 48x-92=1684 x=37 39x+52=2470 x=62 56x-86=2770 x=51 96x+95=3935 x=40 21x-70=1988 x=98 72x+15=7071 x=98 83x-63=7656 x=93 47x+64=1944 x=40 38x+38=1178 x=30 68x+91=4103 x=595x-67=48 x=2346x-74=4112 x=9174x-34=6700 x=913.4-1.4= 7.82-7.2= 2.19+9.1= 10.1-0.89=0.68+0.42= 8.1-5.1= 0.728-0.24= 0.8+0.18=0.89-0.25= 1-0.98= 0.048+0.52= 5×400= 19.9+11.1= 187÷1000= 1+3.89= 0.081×10=75÷10= 0.96÷0.8= 0.8×7= 1.5×7= 1.32×8= 0.7×8= 10.3×2= 5×0.6= 0.9×0.3= 3.5×0.2= 2.01×0= 10×0.05= 0.13×7= 0.21×100=0.7×4= 0.05×4= 4×0.3= 430-250=0.17+0.06= 1.02-0.09= 7200÷800= 0.17+0.6=0.83-0.6= 17×300= 0.98-0.09= 0.2+0.78= 600×700= 10.2+0.02= 0.15+0.7= 670+250=10.2+0.2= 9.2-6= 8500÷500= 3.2-3.2=3.7+2.3= 25×100= 3.2-0.32= 2+2.8=380-290= 0.35+0.5= 0.35+0.63= 3500÷70=3.1+3= 3.8+0.38=7500÷250= 3.8+1= 0.95-0.05= 450+780=3.1+0.3= 3+0.3= 630÷9=4.5-0.4=9.5-5= 330×9= 9.53-1.53= 9.5-0.5=3.5+2.4= 1-0.95= 0.3+0.27= 0.47+0.13=4.5+4= 4-0.6= 0.95+0.05= 2.5+3.2=0.74+0.16= 23×100= 9.8-4.8= 480÷40= 0.53÷100= 5.1+2.3= 125×80= 0.078÷10=0.52+0.4= 70×12=0.25×100= 3.4-2.8= 0.6-0.37= 0.052×10= 10+0.08= 1-0.75= 0.5×1000= .82+0.3=13.5+6.5= 3.05×100= 1.2-0.8= 21.6-12.6=63÷100= 0.83-0.5= 0.76+0.14= 80÷1000=2.7+0.4= 0.72-0.43= 30×100= 0.92-0.2=3.5+4.8= 3.5+2.4= 5+0.07= 1-0.61=0.47+0.23= 0.25+0.75= 3.7+0.33= 0.51+0.33=1-0.6= 8-4.6= 5.8-3.6= 0.52+0.4=6.45+5.5= 4.5-1.3= 3.4-2.8= 9.53-1.53=8.8-6.7= 10+0.08= 9.5-7.3= 7.2+0.8=7.82+0.3= 8.8-6.7= 9.5-7.3= 1-0.95=3.4-2.8= 0.96-0.35= 0.35×0.6= 3.08×0.01=4.95×1000= 6.9×0.1= 0.4×0.5= 2.4÷0.8= 10.8÷9= 9.6÷0.8= 0.108÷2= 4.95÷0.9= 9.65÷0.1= 0.325×100= 2.5×8= 0. 56÷0.7= 0.125×4= 3.28×0.1= 3.9÷0.13=7.2×0.1= 0.01×0.1= 0.25×0.4= 1.6÷0.8= 1÷2.5= 1.25×0.8= 3.2÷0.04= 0÷1.7=4.7+2.3= 4.5×2= 6.9－2.5= 7.2×0.8=6×3.4= 0.62－0.32= 1.4×0.5= 0.75×100=0.02×0.5= 3.6÷0.3= 6.3÷7= 5.6÷100=0.75÷0.25= 0.125×8= 4.8÷0.3=0.96÷2=0.56÷28= 0.36÷0.4= 0.64÷0.8=0.72÷3.6=3.6÷24= 0.8×1.1= 7.2+12.8=46.7－3.8=12.8÷4= 5.2÷13= 12.5÷5= 1.64÷41=10÷20= 24÷15= 8.65×10= 0.35×0.6=3.08×0.01=4.95×1000= 6.9×0.1= 0.4×0.5=2.4÷0.8= 10.8÷9= 9.6÷0.8=0.108÷2=4.95÷0.9= 9.65÷0.1= 0.325×100=2.5×8=0. 56÷0.7= 0.125×4= 3.28×0.1=3.9÷0.13=7.2×0.1= 0.01×0.1= 0.25×0.4=1.6÷0.8=1÷2.5= 1.25×0.8= 3.2÷0.04= 0÷1.7=0.22×102= 9÷0.25÷4= 0.25×3.97×4= （1.2＋8.8）×0.4=50＋160÷40 （58+370）÷（64-45）32.120-144÷18+3533.347+45×2-4160÷5234（58+37）÷（64-9×5）35.95÷（64-45）36.178-145÷5×6+42 420+580-64×21÷2837.812-700÷（9+31×11）（136+64）×（65-345÷23）38.85+14×（14+208÷26）23) 1.2×2.5+0.8×2.524) 8.9×1.25-0.9×1.2525) 12.5×7.4×0.826) 9.9×6.4-（2.5+0.24）（27） 6.5×9.5+6.5×0.50.35×1.6+0.35×3.46.72-3.28-1.720.45+6.37+4.555.4+6.9×3-（25-2.5）2×41846-620-380 4.8×46+4.8×540.8+0.8×2.51.25×3.6×8×2.5-12.5×2.428×12.5-12.5×2023.65-（3.07+3.65）（4+0.4×0.25）8×7×1.251.65×99+1.6527.85-（7.85+3.4）48×1.25+50×1.25×0.2×87.8×9.9+0.78(1010+309+4+681+6）×123×9146×782×6×8545.15×7/8+6.1-0.6062539.（284+16）×（512-8208÷18）40.120-36×4÷18+3541.（58+37）÷（64-9×5）42.(6.8-6.8×0.55)÷8.543.0.12× 4.8÷0.12×4.844.（3.2×1.5+2.5）÷1.6 （2）3.2×（1.5+2.5）÷1.645.6-1.6÷4= 5.38+7.85-5.37=46.7.2÷0.8-1.2×5= 6-1.19×3-0.43=47.6.5×（4.8-1.2×4）= 0.68×1.9+0.32×1.948.10.15-10.75×0.4-5.749.5.8×（3.87-0.13）+4.2×3.7450.32.52-（6+9.728÷3.2）×2.551.[（7.1-5.6）×0.9-1.15] ÷2.552.5.4÷[2.6×（3.7-2.9）+0.62]53.12×6÷（12-7.2）-6 （4）12×6÷7.2-6方程：88x+43=8579 x=9736x+58=2974 x=8113x+25=1247 x=9489x-31=4063 x=4627x+40=445 x=1583x-90=1653 x=2129x-35=545 x=2097x+81=954 x=980x+17=1777 x=22 17x-37=609 x=38 88x+30=2758 x=31 80x+85=565 x=6 49x+43=827 x=16 99x-98=6139 x=63 95x+94=1044 x=10 62x+77=6153 x=98 38x-15=2037 x=54 44x+23=1387 x=31 83x-38=4444 x=54 60x+83=3203 x=52 21x+90=489 x=19 22x+23=2135 x=96 37x+28=509 x=13 67x+39=5466 x=81 92x+67=1079 x=11 38x+45=2021 x=52 64x-67=2813 x=45 5x-96=94 x=3884x-56=4732 x=579x+86=500 x=469x-48=744 x=8843x-94=637 x=1738x-69=2933 x=7923x-40=696 x=3248x-92=1684 x=3739x+52=2470 x=6256x-86=2770 x=5196x+95=3935 x=4021x-70=1988 x=9872x+15=7071 x=9883x-63=7656 x=9347x+64=1944 x=4038x+38=1178 x=3068x+91=4103 x=5953x+65=1443 x=265x-67=48 x=2346x-74=4112 x=9174x-34=6700 x=913.4-1.4= 7.82-7.2= 2.19+9.1= 10.1-0.89= 0.68+0.42= 8.1-5.1= 0.728-0.24= 0.8+0.18=0.89-0.25= 1-0.98= 0.048+0.52= 5×400= 19.9+11.1= 187÷1000= 1+3.89= 0.081×10=75÷10= 0.96÷0.8= 0.8×7= 1.5×7= 1.32×8= 0.7×8= 10.3×2= 5×0.6= 0.9×0.3= 3.5×0.2= 2.01×0= 10×0.05= 0.13×7= 0.21×100=0.7×4= 0.05×4= 4×0.3= 430-250=0.17+0.06= 1.02-0.09= 7200÷800= 0.17+0.6=0.83-0.6= 17×300= 0.98-0.09= 0.2+0.78= 600×700= 10.2+0.02= 0.15+0.7= 670+250=10.2+0.2= 9.2-6= 8500÷500= 3.2-3.2=3.7+2.3= 25×100= 3.2-0.32= 2+2.8=380-290= 0.35+0.5= 0.35+0.63= 3500÷70=3.1+3= 3.8+0.38=7500÷250= 3.8+1= 0.95-0.05= 450+780=3.1+0.3= 3+0.3= 630÷9=4.5-0.4=9.5-5= 330×9= 9.53-1.53= 9.5-0.5=3.5+2.4= 1-0.95= 0.3+0.27= 0.47+0.13=4.5+4= 4-0.6= 0.95+0.05= 2.5+3.2=0.74+0.16= 23×100= 9.8-4.8= 480÷40= 0.53÷100= 5.1+2.3= 125×80= 0.078÷10=0.52+0.4= 70×12=0.25×100= 3.4-2.8= 0.6-0.37= 0.052×10= 10+0.08= 1-0.75= 0.5×1000= .82+0.3=13.5+6.5= 3.05×100= 1.2-0.8= 21.6-12.6= 63÷100= 0.83-0.5= 0.76+0.14= 80÷1000=2.7+0.4= 0.72-0.43= 30×100= 0.92-0.2=3.5+4.8= 3.5+2.4= 5+0.07= 1-0.61=0.47+0.23= 0.25+0.75= 3.7+0.33= 0.51+0.33= 1-0.6= 8-4.6= 5.8-3.6= 0.52+0.4=6.45+5.5= 4.5-1.3= 3.4-2.8= 9.53-1.53= 8.8-6.7= 10+0.08= 9.5-7.3= 7.2+0.8= 7.82+0.3=8.8-6.7=9.5-7.3= 1-0.95=3.4-2.8= 0.96-0.35= 0.35×0.6= 3.08×0.01=4.95×1000= 6.9×0.1= 0.4×0.5= 2.4÷0.8= 10.8÷9= 9.6÷0.8= 0.108÷2= 4.95÷0.9= 9.65÷0.1= 0.325×100= 2.5×8= 0. 56÷0.7= 0.125×4= 3.28×0.1= 3.9÷0.13=7.2×0.1= 0.01×0.1= 0.25×0.4= 1.6÷0.8= 1÷2.5= 1.25×0.8= 3.2÷0.04= 0÷1.7= 4.7+2.3= 4.5×2= 6.9－2.5= 7.2×0.8=6×3.4= 0.62－0.32= 1.4×0.5= 0.75×100=0.02×0.5= 3.6÷0.3= 6.3÷7= 5.6÷100=0.75÷0.25= 0.125×8= 4.8÷0.3= 0.96÷2=0.56÷28= 0.36÷0.4= 0.64÷0.8=0.72÷3.6=3.6÷24= 0.8×1.1= 7.2+12.8= 46.7－3.8=12.8÷4= 5.2÷13= 12.5÷5= 1.64÷41=10÷20= 24÷15= 8.65×10= 0.35×0.6=3.08×0.01=4.95×1000= 6.9×0.1= 0.4×0.5=2.4÷0.8= 10.8÷9= 9.6÷0.8=0.108÷2=4.95÷0.9= 9.65÷0.1= 0.325×100= 2.5×8=0. 56÷0.7= 0.125×4= 3.28×0.1= 3.9÷0.13=7.2×0.1= 0.01×0.1= 0.25×0.4= 1.6÷0.8=1÷2.5= 1.25×0.8= 3.2÷0.04= 0÷1.7=0.22×102= 9÷0.25÷4= 0.25×3.97×4= （1.2＋8.8）×0.4=50＋160÷40 （58+370）÷（64-45）32.120-144÷18+3533.347+45×2-4160÷5234（58+37）÷（64-9×5）35.95÷（64-45）36.178-145÷5×6+42 420+580-64×21÷2837.812-700÷（9+31×11）（136+64）×（65-345÷23）38.85+14×（14+208÷26）23) 1.2×2.5+0.8×2.524) 8.9×1.25-0.9×1.257.8×10= 0.6×100= 3.71×10= 4.5×1000= 0.92×100= 6÷12＝ 0.87－0.49＝5.2×10= 0.28×1000=6.12×10= 0.479×100= 17.6×1000= 5÷100= 21.3÷10=14.17÷100= 9.2÷10= 7.13÷10= 1÷100= 0.43÷10= 278.6÷1000= 53.4÷100=38.2÷100= 2.33÷10= 4.56÷100= 9.02÷10= 70.77÷100= 356.8÷1000= 3.2×3=1.4×0.5= 0.08×6= 1.5×0.3= 0.71×2= 0.25×4= 1.25×8= 4.3×2=1.2×0.4= 0.6×0.9= 3.4×0.3= 5×0.6= 4.5×2= 0.03×0.5= 1.6×0.3=0.23×3= 5.1×2= 9×0.3= 7.1×3=1.5×6= 0.9×0.4×10= 0.68×8×1.25=7.1×0.25×4= 16.4×2.9+16.4×7.1= 3.2×2.8+3.2×7.2= 1/6 + 1/2 -1/6 = 7.5-(2.5+3.8)=7.2÷3= 8.4÷4= 0.65÷5= 0.93÷3= 2.7÷9= 3.8÷2= 5.4÷0.8= 4.6÷2=1.8÷0.3= 4.2÷7= 9.6÷0.6= 6.4÷3.2= 11÷0.11= 10÷2.5= 14÷0.2=0.31÷3= 10.5÷5= 14.7÷0.7= 20÷0.5= 9.6÷1.2= 3.44÷2= 65÷0.3=9.9÷11= 2.8÷2= 0.96÷3= 17×40＝ 100－63＝ 3.2＋1.68＝ 2.8×0.4＝14－7.4＝ 1.92÷0.04＝ 0.32×500＝ 0.65＋4.35＝ 10－5.4＝ 4÷20＝ 3.5×200＝1.5－0.06＝ 0.75÷15＝ 0.4×0.8＝ 4×0.25＝ 0.36＋1.54＝ 1.01×99＝ 420÷35＝25×12＝ 135÷0.5＝ 3/4 + 1/4 = 2 + 4/9 = 3 - 2/3 = 3/4 - 1/2= 7/8 + 3/8 =3/10 +1/5 = 4/5 - 7/10 = 2 - 1/6 -1/3 = 0.51÷17＝ 32.8＋19＝ 5.2÷1.3＝ 1.6×0.4＝4.9×0.7＝ 1÷5＝活动目的：教育学生懂得“水”这一宝贵资源对于我们来说是极为珍贵的，每个人都要保护它，做到节约每一滴水，造福子孙万代。

五年级数学题口算一、小数加法。

1. 0.3 + 0.4 = 0.7- 解析：小数加法计算时，将小数点对齐，然后按照整数加法的方法进行计算，3加4等于7，小数点位置不变，结果是0.7。

2. 1.2+0.5 = 1.7- 解析：把1.2和0.5的小数点对齐，2加5等于7，1加0等于1，结果是1.7。

3. 0.8+0.9 = 1.7- 解析：先将小数点对齐，8加9等于17，满十进一，所以结果是1.7。

4. 2.3 + 0.6 = 2.9- 解析：小数点对齐后，3加6等于9，2加0等于2，得到2.9。

5. 1.5+0.8 = 2.3- 解析：1.5和0.8小数点对齐相加，5加8等于13，进1，1加1等于2，结果是2.3。

二、小数减法。

6. 0.9 - 0.5 = 0.4- 解析：小数点对齐，9减5等于4，小数点位置不变，结果为0.4。

7. 1.7-0.9 = 0.8- 解析：1.7和0.9小数点对齐，7减9不够减，从1借1当10，17 - 9=8，1被借走1剩0，结果是0.8。

8. 2.5 - 1.8 = 0.7- 解析：小数点对齐，5减8不够减，从2借1当10，15 - 8 = 7，2被借走1剩1，1 - 1=0，结果是0.7。

9. 3.6-2.9 = 0.7- 解析：小数点对齐，6减9不够减，从3借1当10，16 - 9 = 7，3被借走1剩2，2 - 2 = 0，结果是0.7。

10. 1.3 - 0.7 = 0.6- 解析：小数点对齐，3减7不够减，从1借1当10，13 - 7 = 6，1被借走1剩0，结果是0.6。

三、整数乘小数。

11. 3×0.2 = 0.6- 解析：计算3×0.2时，把0.2看作2，3×2 = 6，然后因为0.2有一位小数，从6的右边起数出一位点上小数点，结果是0.6。

12. 5×0.4 = 2- 解析：把0.4看作4，5×4 = 20，0.4有一位小数，从20右边起数出一位点上小数点，结果是2。