小数乘法计算道含答案

小数乘法计算道含小数乘法计算600道第一部分一．计算（共50小题）1．直接写出得数．0.4×0.02=1.8×0.4=6×0.25=1.25×0.8=3﹣0.98=0.9÷0.01=3.9×0.01=99×0.25=2．用竖式计算下面各题．2.4×1.5=0.46×8.7=（保留一位小数）2.24×1.8=（保留两位小数）3．用竖式计算．（得数保留两位小数）3.35×1.7≈5.63×3.9≈4．用竖式计算．2.97×3.5=6.05×0.83=0.78×4.5=3.36×3.67=5．直接写得数．6.2×0.3=2.5×0.8=0.06×5=0.16×25=5×2.1=0×48.76=6．用竖式计算（计算结果小数部分超过两位的，保留两位小数）．6.02×0.35  0.59÷1.4．7．按要求算一算．2.9×1.84.58×0.370.8×2.5（得数保留一位小数）　5.45×1.72（得数保留两位小数）8．列竖式计算：1.8×0.85=7.6﹣2.19=50﹣18.75=9．用竖式计算．4.68×1.2=1.58×2.5=10．竖式计算．1.35×270        6.4×8.05．11．用竖式计算．36×5.518×3.063.45×210.28×0.25150×0.120.87×1.50.4×0.0761.5×0.0626.5×0.0412．竖式计算．0.94×5.3=0.91×2.6=4.06×0.75（保留两位小数）≈8.43×1.5=0.25×3.2=7.8×0.9（保留一位小数）≈13．直接写出得数．0.25×4=1.25×8=8.2×6.9×0=0.2×18=6.29×100=0.02×500=3.4×2=0.26×0.5=14．我会口算．0.5×4.4=80÷1.6=5.5÷0.11=0.06×5=5×0.4×0.8=9.9+10.1=1.25×0.8=0.08÷0.1=4﹣0.15=1.7×5+0.3×5=15．口算．3π=5π=5×3.14=0.5×7=92=62﹣32=4π﹣1.5π=34.6÷0.5=16．用竖式计算，得数保留一位小数．2.4×6.7≈3.5×0.5≈17．直接写出得数．0.8×25=0×4.23=0.57+0.43=2.4×0.2=0.02×500=2.8×10=8.29×100=2.5×0.4=4.87﹣1.7=18．列竖式计算．0.64×12.5=2.8×0.17=19．直接写出得数．0.7×0.9=0.14×0.3=5.5×10=2.6×0.5=20．用竖式计算2.75×3.1=3.18×5.45=0.76×2.18≈（得数保留两位小数）0.09×1.7≈（精确到十分位）21．列竖式计算0.36×0.15=（得数保留两位小数）     1.45×0.12=0.86×1.4=（得数保留一位小数）     6.5×0.39=22．用竖式计算．8×0.12=1.9×3.5=2.3×1.29=（验算）0.401×0.3=0.45×0.96=0.17×0.71=（得数保留两位小数）23．直接写得数．70×0.01=2.515×10=1.1×0.4=10﹢0.3=6.5×0.2=0.1×0.01=0.87﹣0.6=1.7×3=24．竖式计算．（得数保留一位小数）0.38×0.235.79×3.64.6×0.25．25．竖式计算．3.6×0.25=9.8﹣1.64=3.1×300=26．口算．0.7×0.5=3.6×2=0.4×1.7=4.5×6=0.36+9=5.7+3=6.6×2=0.1×3.1=27．直接写出计算结果0.3×1.1=5.79+2.31+4.21=0.25×4=1.2÷0.4=1.5×0.6=1.59÷0.3=0.5×101=6.5﹣5=10﹣8.88﹣0.12=0.64÷1.6×1.5=28．直接写得数．0.6×0.7=0.8×5=1.1×0.4=2.3×4×0=0.05×1.6=0.02×7=29．用竖式计算．0.32×0.8=1.36×4.8=17.3×0.06=30．用竖式计算．1.45×0.12=3.08×0.28=13.5×26.7=3.15×0.35≈（保留一位小数）31．口算．9.37×0=7.3×100=289+72﹣89=1﹣0.04=4×8÷8×4=32．列竖式计算：30.5×0.76         0.54×0.19．33．直接写得数：2.5×33.06×20.25×44.2×105.3×1002.5×62.2×41.6×41.25×834．竖式计算0.38×0.25=0.12×15=8.5×0.39=（验算）   0.87×1.5（保留二位小数）35．用竖式计算并验算．14.53+5.677.2﹣6.451.05×2.862.9÷1.7．36．口算：0.5×2=0.25×4=12.5×8=0.125×8=7÷0.7=1﹣0.125×8=1.25×32=0.25×56=37．口算0.2×0.4=8.2+1.8=6.45×0.01=2.5×0.4=0.8×50=2.4×5=0.9﹣0.52=10.2×4.5=38．竖式计算，带*的要验算*4.23×0.02836×0.5631.5×24.50.8×0.56*0.63×1.051.8×3.6739．竖式计算35.4×0.8  7.63×1.2  0.08×1.143.17×2.8（得数保留两位小数）      0.3×5.6（得数保留一位小数）          54.3×0.7（得数保留整数）40．列竖式计算24.6÷12  4.32÷1.2   21÷0.15．41．直接写出得数0×7=2.6+0.4=15×0.01=21.2﹣21=1.8a+0.2a=0.4×0.4=0.12×0.04=0.8×100=2.5×4×0=0.72×0.8=42．口算．0.12×100=6.2×10=500÷1000=12万+3万=8a+a=6.2÷10=3.74×100=23.6÷100=3.25×10=43．竖式计算0.18×123.26×153.1×171.25×414×0.58.4×150.45×91.5×350.02×134.28×162.61×1844．直接写出得数．40×1.2=25×0.4=63=7.8+0.9=0.56+4.44=2.4×0.5=1.25×80=3.6÷0.06=12÷0.4=82=45．列竖式计算2.034×184.06×3.8（积保留两位小数）46．计算4×38.2=8×0.352=35.6×5=6.7×3=47．口算9.5×0.2=3.2×0.5=0.8×2.5=4.4×0.4=35×0.4=4.8×50=4.8×0.25=8.8×5=1.4×0.5=12.5×4=48．竖式计算．☆0.43×27=1.85×2.6=验算：0.37×2.4≈（得数保留一位小数） 7.02×0.56≈（得数保留两位小数）49．直接写出得数．0.7×0.9=2.6×0.5=0.14×0.3=5.5×10=1.7×0.03=1.8×0.04=0.12×6=4.8×5=50．竖式计算．5.6×1.8=0.25×0.046≈（保留两位小数）3500×0.96=第二部分一．计算题（共50小题）1．列竖式计算：1.8×0.36=35.37+28.63=19.9﹣8.75=1.06×0.48=18.9+28.65=22.87﹣18.65=2．用竖式计算下面各题．2.4×1.5=0.46×8.7=（保留一位小数）2.24×1.8=（保留两位小数）3．直接写得数．0.102×100=4.2+3=0.23×0.5=0.25×7×0.4=3.6÷0.6=42=0.1÷0.01=2×0.5+1=4．用竖式计算（计算结果小数部分超过两位的，保留两位小数）．6.02×0.358.74÷3.80.59÷1.4．5．列竖式计算：1.8×0.85=7.6﹣2.19=50﹣18.75=6．用竖式计算．4.8×0.259.3×1.39.8×0.52.1×2.15．7．用竖式计算．（得数保留两位小数）3.35×1.7≈5.63×3.9≈8．直接写出得数．0.12×0.4=3.8÷100=56.56÷0.561.6+3.04=19.28﹣0.8=2.8÷0.7=0.53×1000=108÷2.5÷4=9．列竖式计算3.48×1.05（计算并验算）1.55÷3.8（得数保留两位小数）10．竖式计算0.64×18=25.8×102=40.7×0.25=13.45×2.6=（保留整数）4.865×8≈（保留整数）10.23×42≈（保留一位小数）11．直接写得数．6.2×0.3=2.5×0.8=0.06×5=0.16×25=5×2.1=0×48.76=12．按要求算一算．2.9×1.8   　4.58×0.370.8×2.5（得数保留一位小数） 5.45×1.72（得数保留两位小数）13．用竖式计算．84×0.25=0.55×64=0.47×5.8=6.06×0.32=0.075×0.07=3.7×9.77=14．列竖式计算．3.4×0.25  　6.5×2.40.035×0.6 1.25×0.024．15．用竖式计算．2.97×3.5=6.05×0.83=0.78×4.5=3.36×3.67=16．用竖式计算．36×5.518×3.063.45×210.28×0.25150×0.120.87×1.50.4×0.0761.5×0.0626.5×0.0417．竖式计算4.57×1.8     0.125×0.8      3.75×0.249.37×8.5     2.07×3.6      3.35×1.6．18．竖式计算．0.94×5.3=0.91×2.6=4.06×0.75（保留两位小数）≈8.43×1.5=0.25×3.2=7.8×0.9（保留一位小数）≈19．我会口算．0.5×4.4=80÷1.6=5.5÷0.11=0.06×5=5×0.4×0.8=9.9+10.1=1.25×0.8=0.08÷0.1=4﹣0.15=1.7×5+0.3×5=20．列竖式计算，带*号的要验算．25.78+3.12=13.8×9=*8﹣2.67=*5.73+6.7=21．直接写出得数．0.125×100=60÷100=9÷10=0.32+4.68=15.7+4.3=25×4=10﹣0.8=7×99+7=14.6+0.34=30.5+2.5=24﹣7.54﹣2.46=26+19+74+81=22．用竖式计算．4.68×1.2=1.58×2.5=23．用竖式计算，得数保留一位小数．2.4×6.7≈3.5×0.5≈24．竖式计算7.6×0.82=3.25×0.31=7.5×0.59=（验算）25．口算．3π=5π=5×3.14=0.5×7=92=62﹣32=4π﹣1.5π=34.6÷0.5=26．直接写出得数．0.8×25=0×4.23=0.57+0.43=2.4×0.2=0.02×500=2.8×10=8.29×100=2.5×0.4=4.87﹣1.7=27．列竖式计算．0.64×12.5=2.8×0.17=28．列竖式计算4.8×171.88×252.4×0.370.89×5.3．29．列竖式计算．（得数保留两位小数）2.375×105    　5.16×4.3    　0.45×0.206．30．列竖式计算．0.04×0.12  4.25×8.83.84×0.25．31．竖式计算．3.6×0.25=9.8﹣1.64=3.1×300=32．用竖式计算2.75×3.1=3.18×5.45=0.76×2.18≈（得数保留两位小数）0.09×1.7≈（精确到十分位）33．列竖式计算0.36×0.15=（得数保留两位小数）     1.45×0.12=0.86×1.4=（得数保留一位小数）     6.5×0.39=34．用竖式计算．8×0.12=1.9×3.5=2.3×1.29=（验算）0.401×0.3=0.45×0.96=0.17×0.71=（得数保留两位小数）35．直接写出得数．0.7×0.9=0.14×0.3=5.5×10=2.6×0.5=36．列竖式计算：30.5×0.76         0.54×0.19．37．竖式计算．1.35×270         6.4×8.05．38．直接写得数．70×0.01=2.515×10=1.1×0.4=10﹢0.3=6.5×0.2=0.1×0.01=0.87﹣0.6=1.7×3=39．列竖式计算24.6÷12  4.32÷1.2   21÷0.15．40．直接写出得数．0×7=2.6+0.4=15×0.01=21.2﹣21=1.8a+0.2a=0.4×0.4=0.12×0.04=0.8×100=2.5×4×0=0.72×0.8=41．竖式计算．（得数保留一位小数）0.38×0.235.79×3.64.6×0.25．42．用竖式计算．0.32×0.8=1.36×4.8=17.3×0.06=43．竖式计算（*验算）8.4×0.15=16.51﹣6.3=900﹣4.58=*56.7+0.33=44．口算．0.7×0.5=3.6×2=0.4×1.7=4.5×6=0.36+9=5.7+3=6.6×2=0.1×3.1=45．用竖式计算．1.45×0.12=3.08×0.28=13.5×26.7=3.15×0.35≈（得数保留一位小数）46．竖式计算0.38×0.25=0.12×15=8.5×0.39=（验算）   0.87×1.5 （得数保留二位小数）47．直接写出计算结果0.3×1.1=5.79+2.31+4.21=0.25×4=1.2÷0.4=1.5×0.6=1.59÷0.3=0.5×101=6.5﹣5=10﹣8.88﹣0.12=0.64÷1.6×1.5=48．竖式计算0.38×0.25150×0.120.87×1.91.28×2.32.07×0.240.17×1.0549．用竖式计算．8×0.12=（验算）      1.9×3.5=（验算）0.401×0.3=0.45×0.96=0.17×0.71=50．直接写出得数．0.13×0.2=1﹣0.9=0.32÷2=0.8×5=0.9×0.1=3.11+2.22=0.52=8m﹣6m=1.62﹣0.62=5.9+4.4=0.053×100=12.5+12.5×7=第一部分参考答案与试题解析一．计算题（共50小题）1．【解答】解：0.4×0.02=0.0081.8×0.4=0.726×0.25=1.51.25×0.8=13﹣0.98=2.020.9÷0.01=903.9×0.01=0.03999×0.25=24.752．【解答】解：（1）2.4×1.5=3.6（2）0.46×8.7≈4.0（3）2.24×1.8≈4.03　3．【解答】解：3.35×1.7≈5.705.63×3.9≈21.96　4．【解答】解：2.97×3.5=10.3956.05×0.83=5.02150.78×4.5=3.513.36×3.67=12.3312　5．【解答】解：6.2×0.3=1.862.5×0.8=20.06×5=0.30.16×25=45×2.1=10.50×48.76=06．【解答】解：6.02×0.35≈2.118.74÷3.8=2.30.59÷1.4≈0.42　7．【解答】解：2.9×1.8=5.224.58×0.37=1.69460.8×2.5=2.05.45×1.72≈9.37　8．【解答】解：1.8×0.85=1.537.6﹣2.19=5.4150﹣18.75=31.25　9．【解答】解：4.68×1.2=5.6161.58×2.5=3.95　10．【解答】解：1.35×270=368.5         6.4×8.05=51.52　11．【解答】解：（1）36×5.5=198；（2）18×3.06=55.08；          （3）3.45×21=72.45；（4）0.28×0.25=0.07；        （5）150×0.12=18；     （6）0.87×1.5=1.305；（7）0.4×0.076=0.0304；　    （8）1.5×0.062=0.093； （9）6.5×0.04=0.26．　12．【解答】解：（1）0.94×5.3=4.982；（2）0.91×2.6=2.366；（3）4.06×0.75≈3.05；（4）8.43×1.5=12.645；（5）0.25×3.2=0.8；（6）7.8×0.9≈7.0．　13．【解答】解：0.25×4=11.25×8=108.2×6.9×0=00.2×18=3.66.29×100=6290.02×500=103.4×2=6.80.26×0.5=0.1314．【解答】解：0.5×4.4=2.280÷1.6=505.5÷0.11=500.06×5=0.35×0.4×0.8=1.69.9+10.1=201.25×0.8=10.08÷0.1=0.84﹣0.15=3.851.7×5+0.3×5=1015．【解答】解：3π=9.425π=15.75×3.14=15.70.5×7=3.592=8162﹣32=274π﹣1.5π=7.8534.6÷0.5=69.216．【解答】解：2.4×6.7≈16.13.5×0.5≈1.8　17．【解答】解：0.8×25=20×4.23=00.57+0.43=12.4×0.2=0.480.02×500=102.8×10=288.29×100=8292.5×0.4=14.87﹣1.7=3.1718．【解答】解：（1）0.64×12.5=8（2）2.8×0.17=0.476　19．【解答】解：0.7××0.3=0.0425.5×10=552.6×0.5=1.3．　20．【解答】解：（1）2.75×3.1=8.525（2）3.18×5.45=17.331（3）0.76×2.18≈1.66（得数保留两位小数）（4）0.09×1.7≈0.2（精确到十分位）　21．【解答】解：0.36×0.15≈0.051.45×0.12=0.1740.86×1.4≈0.16.5×0.39=2.535　22．【解答】解：8×0.12=0.961.9×3.5=6.652.3×1.29=2.9670.401×0.3=0.12030.45×0.96=0.4320.17×0.71≈0.12　23．【解答】解：70×0.01=0.72.515×10=25.151.1×0.4=0.4410﹢0.3=10.36.5×0.2=1.30.1×0.01=0.0010.87﹣0.6=0.271.7×3=5.124．【解答】解：0.38×0.23≈0.15.79×3.6≈20.84.6×0.25≈1.2　25．【解答】解：3.6×0.25=0.99.8﹣1.64=8.163.1×300=930　26．【解答】解：0.7×0.5=0.353.6×2=7.20.4×1.7=0.684.5×6=270.36+9=9.365.7+3=8.76.6×2=13.20.1×3.1=0.3127．【解答】解：0.3×1.1=0.335.79+2.31+4.21=12.310.25×4=11.2÷0.4=31.5×0.6=0.91.59÷0.3=5.30.5×101=50.56.5﹣5=1.510﹣8.88﹣0.12=10.64÷1.6×1.5=0.628．【解答】解：0.6×0.7=0.420.8×5=41.1×0.4=0.442.3×4×0=00.05×1.6=0.080.02×7=0.1429．【解答】解：0.32×0.8=0.2561.36×4.8=6.52817.3×0.06=1.038　30．【解答】解：1.45×0.12=0.1743.08×0.28=0.862413.5×26.7=360.453.15×0.35≈1.1　31．【解答】解：9.37×0=07.3×100=730289+72﹣89=2721﹣0.04=0.964×8÷8×4=16　32．【解答】解：30.5×0.76=23.18         0.54×0.19=0.1026　33．【解答】解：2.5×3=7.53.06×2=6.120.25×4=14.2×10=425.3×100=5302.5×6=152.2×4=8.81.6×4=6.41.25×8=1034．【解答】解：0.38×0.25=0.0950.12×15=1.88.5×0.39=3.315   0.87×1.5≈1.31　35．【解答】解：①14.53+5.67=20.2②7.2﹣6.45=0.75③1.05×2.8=2.94验算：④62.9÷1.7=37验算：　36．【解答】解：0.5×2=10.25×4=112.5×8=1000.125×8=17÷0.7=101﹣0.125×8=01.25×32=800.25×56=1437．【解答】解：0.2×0.4=0.088.2+1.8=106.45×0.01=0.06452.5×0.4=10.8×50=402.4×5=120.9﹣0.52=0.2810.2×4.5=45.938．【解答】解：*4.23×0.028=0.1184436×0.56=20.1631.5×24.5=771.750.8×0.56=0.448*0.63×1.05=0.66151.8×3.67=6.606　39．【解答】解：35.4×0.8=28.32     7.63×1.2=9.156      0.08×1.14=0.09123.17×2.8≈8.88；     0.3×5.6≈1.7        54.3×0.7≈4　40．【解答】解：24.6÷12=2.05  4.32÷1.2=3.6   21÷0.15=140　41．【解答】解：0×7=02.6+0.4=315×0.01=0.1521.2﹣21=0.21.8a+0.2a=2a0.4×0.4=0.160.12×0.04=0.00480.8×100=802.5×4×0=00.72×0.8=0.57642．【解答】解：0.12×100=126.2×10=62500÷1000=0.512万+3万=15万8a+a=9a6.2÷10=0.623.74×100=37423.6÷100=0.2363.25×10=32.543．【解答】解：（1）0.18×12=2.16（2）3.26×15=48.9（3）3.1×17=52.7（4）1.25×4=5（5）14×0.5=7（6）8.4×15=126   （7）0.45×9=4.05   （8）1.5×35=52.5（9）0.02×13=0.26  （10）4.28×16=68.48（11）2.61×18=46.98　44．【解答】解：40×1.2=4825×0.4=1063=2167.8+0.9=8.70.56+4.44=52.4×0.5=1.21.25×80=1003.6÷0.06=6012÷0.4=3082=6445．【解答】解：①2.034×18=36.612②4.06×3.8≈15.43　46．【解答】解：4×38.2=152.88×0.352=2.81635.6×5=1786.7×3=20.1　47．【解答】解：9.5×0.2=1.93.2×0.5=1.60.8×2.5=24.4×0.4=1.7635×0.4=144.8×50=2404.8×0.25=1.28.8×5=441.4×0.5=0.712.5×4=5048．【解答】解：0.43×27=11.61；1.85×2.6=4.81；0.37×2.4≈0.9（得数保留一位小数）；7.02×0.56≈3.93（得数保留两位小数）；　49．【解答】解：0.7×0.9=0.632.6×0.5=1.30.14×0.3=0.0425.5×10=551.7×0.03=0.0511.8×0.04=0.0720.12×6=0.724.8×5=2450．【解答】解：5.6×1.8=10.08  0.25×0.046≈0.013500×0.96=3360　第二部分参考答案与试题解析一．计算题（共50小题）1．【解答】解：1.8×0.36=0.64835.37+28.63=6419.9﹣8.75=11.151.06×0.48=0.508818.9+28.65=47.5522.87﹣18.65=4.22　2．【解答】解：（1）2.4×1.5=3.6（2）0.46×8.7≈4.0（3）2.24×1.8≈4.03　3．【解答】解：0.102×100=1024.2+3=7.20.23×0.5=0.1150.25×7×0.4=0.73.6÷0.6=642=160.1÷0.01=102×0.5+1=24．【解答】解：6.02×0.35≈2.118.74÷3.8=2.30.59÷1.4≈0.42　5．【解答】解：1.8×0.85=1.537.6﹣2.19=5.4150﹣18.75=31.25　6．【解答】解：4.8×0.25=1.29.3×1.3=12.099.8×0.5=4.92.1×2.15=4.515　7．【解答】解：3.35×1.7≈5.705.63×3.9≈21.96　8．【解答】解：0.12×0.4=0.0483.8÷100=0.03856.56÷0.56=1011.6+3.04=4.6419.28﹣0.8=18.482.8÷0.7=40.53×1000=530108÷2.5÷4=10.89．【解答】解：3.48×1.05=3.654验算：1.55÷3.8≈0.41　10．【解答】解：0.64×18=11.5225.8×102=2631.640.7×0.25=10.17513.45×2.6≈354.865×8≈3910.23×42≈429.7　11．【解答】解：6.2×0.3=1.862.5×0.8=20.06×5=0.30.16×25=45×2.1=10.50×48.76=012．【解答】解：2.9×1.8=5.224.58×0.37=1.69460.8×2.5=2.05.45×1.72≈9.37　13．【解答】解：84×0.25=210.55×64=35.20.47×5.8=2.7266.06×0.32=1.93920.075×0.07=0.005253.7×9.77=36.149　14．【解答】解：①3.4×0.25=0.85②6.5×2.4=15.6③0.035×0.6=0.021 ④1.25×0.024=0.03　15．【解答】解：2.97×3.5=10.3956.05×0.83=5.02150.78×4.5=3.513.36×3.67=12.3312　16．【解答】解：（1）36×5.5=198；（2）18×3.06=55.08；          （3）3.45×21=72.45；（4）0.28×0.25=0.07；        （5）150×0.12=18；     （6）0.87×1.5=1.305；（7）0.4×0.076=0.0304；　    （8）1.5×0.062=0.093； （9）6.5×0.04=0.26．　17．【解答】解：（1）4.57×1.8=8.226；（2）0.125×0.8=0.1；（3）3.75×0.24=0.9；（4）9.37×8.5=79.645；（5）2.07×3.6=7.452；（6）3.35×1.6=5.36．　18．【解答】解：（1）0.94×5.3=4.982；（2）0.91×2.6=2.366；（3）4.06×0.75≈3.05；（4）8.43×1.5=12.645；（5）0.25×3.2=0.8；（6）7.8×0.9≈7.0．　19．【解答】解：0.5×4.4=2.280÷1.6=505.5÷0.11=500.06×5=0.35×0.4×0.8=1.69.9+10.1=201.25×0.8=10.08÷0.1=0.84﹣0.15=3.851.7×5+0.3×5=1020．【解答】解：25.78+3.12=28.913.8×9=124.2*8﹣2.67=5.33验算：*5.73+6.7=12.43验算：　21．【解答】解：0.125×100=12.560÷100=0.69÷10=0.90.32+4.68=515.7+4.3=2025×4=10010﹣0.8=9.27×99+7=70014.6+0.34=14.9430.5+2.5=3324﹣7.54﹣2.46=1426+19+74+81=20022．【解答】解：4.68×1.2=5.6161.58×2.5=3.95　23．【解答】解：2.4×6.7≈16.13.5×0.5≈1.8　24．【解答】解：（1）7.6×0.82=6.232；（2）3.25×0.31=1.0075；（3）7.5×0.59=4.425．　25．【解答】解：3π=9.425π=15.75×3.14=15.70.5×7=3.592=8162﹣32=274π﹣1.5π=7.8534.6÷0.5=69.226．【解答】解：0.8×25=20×4.23=00.57+0.43=12.4×0.2=0.480.02×500=102.8×10=288.29×100=8292.5×0.4=14.87﹣1.7=3.1727．【解答】解：（1）0.64×12.5=8（2）2.8×0.17=0.476　28．【解答】解：4.8×17=81.61.88×25=472.4×0.37=0.8880.89×5.3=4.717　29．【解答】解：2.375×105≈249.38    　5.16×4.3≈22.19    　0.45×0.206≈0.09　30．【解答】解：0.04×0.12=0.0048 4.25×8.8=37.43.84×0.25=0.952　31．【解答】解：3.6×0.25=0.99.8﹣1.64=8.163.1×300=930　32．【解答】解：（1）2.75×3.1=8.525（2）3.18×5.45=17.331（3）0.76×2.18≈1.66（得数保留两位小数）（4）0.09×1.7≈0.2（精确到十分位）　33．【解答】解：0.36×0.15≈0.051.45×0.12=0.1740.86×1.4≈0.16.5×0.39=2.535　34．【解答】解：8×0.12=0.961.9×3.5=6.652.3×1.29=2.9670.401×0.3=0.12030.45×0.96=0.4320.17×0.71≈0.12　35．【解答】解：0.7××0.3=0.0425.5×10=552.6×0.5=1.3．　36．【解答】解：30.5×0.76=23.18         0.54×0.19=0.1026　37．【解答】解：1.35×270=368.5         6.4×8.05=51.52　38．【解答】解：70×0.01=0.72.515×10=25.151.1×0.4=0.4410﹢0.3=10.36.5×0.2=1.30.1×0.01=0.0010.87﹣0.6=0.271.7×3=5.139．【解答】解：24.6÷12=2.05  4.32÷1.2=3.6   21÷0.15=140　40．【解答】解：0×7=02.6+0.4=315×0.01=0.1521.2﹣21=0.21.8a+0.2a=2a0.4×0.4=0.160.12×0.04=0.00480.8×100=802.5×4×0=00.72×0.8=0.57641．【解答】解：0.38×0.23≈0.15.79×3.6≈20.84.6×0.25≈1.2　42．【解答】解：0.32×0.8=0.2561.36×4.8=6.52817.3×0.06=1.038　43．【解答】解：8.4×0.15=1.2616.51﹣6.3=10.21900﹣4.58=895.42*56.7+0.33=57.03　44．【解答】解：0.7×0.5=0.353.6×2=7.20.4×1.7=0.684.5×6=270.36+9=9.365.7+3=8.76.6×2=13.20.1×3.1=0.3145．【解答】解：1.45×0.12=0.1743.08×0.28=0.862413.5×26.7=360.453.15×0.35≈1.1　46．【解答】解：0.38×0.25=0.0950.12×15=1.88.5×0.39=3.315   0.87×1.5≈1.31　47．【解答】解：0.3×1.1=0.335.79+2.31+4.21=12.310.25×4=11.2÷0.4=31.5×0.6=0.91.59÷0.3=5.30.5×101=50.56.5﹣5=1.510﹣8.88﹣0.12=10.64÷1.6×1.5=0.648．【解答】解：0.38×0.25=0.095150×0.12=180.87×1.9=1.6531.28×2.3=2.9442.07×0.24=0.49680.17×1.05=0.1785　49．【解答】解：①8×0.12=0.96  ②1.9×3.5=6.65③0.401×0.3=0.1203④0.45×0.96=0.432⑤0.17×0.71=0.1207　50．【解答】解：0.13×0.2=0.0261﹣0.9=0.10.32÷2=0.160.8×5=40.9×0.1=0.093.11+2.22=5.330.52=0.258m﹣6m=2m1.62﹣0.62=15.9+4.4=10.30.053×100=5.312.5+12.5×7=100