解:23+4.7=27.7, | 10-2.3,7.7, | 0.6-0.23=0.37, | 0.55+0.45=1, | 0.06×0.7=0.042 |
7.5×4=30, | 2.3×4×0,0 | 16÷32=0.5, | 3.5÷5=0.7, | 0.125×80=10, |
分析:23+4.7、10-2.3、0.6-0.23和0.55+0.45小數(shù)的加減法,注意小數(shù)點(diǎn)對(duì)齊,也就數(shù)相同的數(shù)位對(duì)齊,從低位加(或減)起;0.06×0.7、7.5×4和0.125×80按整數(shù)乘法的法則進(jìn)行計(jì)算,再看因數(shù)中一共有幾位小數(shù),就從積德末尾起,數(shù)出幾位,點(diǎn)上小數(shù)點(diǎn);2.3×4×0,因?yàn)?和任何數(shù)相乘都得0,所以2.3×4×0=0;16÷32和3.5÷5,從被除數(shù)的高位起,先看除數(shù)有幾位,再用除數(shù)試除被除數(shù)的前幾位,如果它比除數(shù)小,再試除多一位數(shù);除到被除數(shù)的哪一位,就在那一位上面寫上商,每次除后余下的數(shù)必須比除數(shù)。
點(diǎn)評(píng):此題考查同學(xué)們快速計(jì)算的能力,注意計(jì)算小數(shù)的加減法,注意小數(shù)點(diǎn)對(duì)齊,小數(shù)乘法注意小數(shù)的位數(shù),除數(shù)是整數(shù)的小數(shù)除法,先看除數(shù)有幾位,再用除數(shù)試除被除數(shù)的前幾位,如果它比除數(shù)小,再試除多一位數(shù);除到被除數(shù)的哪一位,就在那一位上面寫上商,每次除后余下的數(shù)必須比除數(shù)小.