分?jǐn)?shù)的乘除法比百分?jǐn)?shù)（課件）六年級(jí)上冊(cè)數(shù)學(xué)蘇教版

蘇教版六年級(jí)上冊(cè)分?jǐn)?shù)的乘除法、比、百分?jǐn)?shù)復(fù)習(xí)回顧一長(zhǎng)方體和正方體································································1

表面涂色的正方體····························································26二分?jǐn)?shù)乘法·········································································28三分?jǐn)?shù)除法·········································································43樹(shù)葉中的比······································································66四解決問(wèn)題的策略································································68五分?jǐn)?shù)四則混合運(yùn)算·····························································75六百分?jǐn)?shù)············································································84互聯(lián)網(wǎng)的普及·································································110七整理與復(fù)習(xí)·····································································112

本學(xué)期我們學(xué)習(xí)了分?jǐn)?shù)的哪些運(yùn)算？還學(xué)習(xí)了有關(guān)比和百分?jǐn)?shù)的哪些知識(shí)？你能用這些知識(shí)解決哪些實(shí)際問(wèn)題？數(shù)的世界分?jǐn)?shù)乘除法分?jǐn)?shù)乘除法的計(jì)算分?jǐn)?shù)的四則混合運(yùn)算運(yùn)算律的推廣比比的意義比的基本性質(zhì)及求比值化簡(jiǎn)比比的讀寫百分?jǐn)?shù)百分?jǐn)?shù)的意義百分?jǐn)?shù)的讀寫百分?jǐn)?shù)與小數(shù)、分?jǐn)?shù)的改寫分?jǐn)?shù)、百分?jǐn)?shù)、比的應(yīng)用分?jǐn)?shù)乘法的應(yīng)用百分?jǐn)?shù)的應(yīng)用納稅、利息和折扣分?jǐn)?shù)除法的應(yīng)用按比分配的實(shí)際問(wèn)題分?jǐn)?shù)與整數(shù)相乘：分?jǐn)?shù)乘法分?jǐn)?shù)與分?jǐn)?shù)相乘：先約分再計(jì)算，計(jì)算結(jié)果要約成最簡(jiǎn)分?jǐn)?shù)

用分子與整數(shù)相乘的積作分子，分母不變；計(jì)算時(shí)能約分的要先約分再計(jì)算。

用分子相乘的積作分子，分母相乘的積作分母。乘積是1的兩個(gè)數(shù)互為倒數(shù)。

分?jǐn)?shù)除法分?jǐn)?shù)除法計(jì)算法則：

甲數(shù)除以乙數(shù)（0除外），等于甲數(shù)乘乙數(shù)的倒數(shù)。分?jǐn)?shù)的四則混合運(yùn)算分?jǐn)?shù)四則混合運(yùn)算的運(yùn)算順序：

分?jǐn)?shù)四則混合運(yùn)算的運(yùn)算順序與整數(shù)、小數(shù)四則混合運(yùn)算的運(yùn)算順序相同。先乘除后加減，有括號(hào)的要先算括號(hào)里面的。運(yùn)算律的推廣加法交換律a+b=b+a加法結(jié)合律（a+b）+c=a+（b+c）乘法交換律a×b=b×a乘法結(jié)合律(a×b)×c=a×(b×c)乘法分配律a×(b+c)=a×b+a×c整數(shù)、小數(shù)的運(yùn)算律對(duì)分?jǐn)?shù)的運(yùn)算也同樣適用下面各題怎樣簡(jiǎn)便就怎樣算。

=82∶3“∶”是比號(hào)，比號(hào)前面的數(shù)叫作比的前項(xiàng)，比號(hào)后面的數(shù)叫作比的后項(xiàng)。

=

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=2332比（比的后項(xiàng)不能為0。）兩個(gè)數(shù)相除又可以叫作兩個(gè)數(shù)的比。比的前項(xiàng)除以后項(xiàng)所得的商叫作比值。比的前項(xiàng)相當(dāng)于被除數(shù)或分子比的后項(xiàng)相當(dāng)于除數(shù)或分母比值相當(dāng)于商或分?jǐn)?shù)值比比的基本性質(zhì)：

比的前項(xiàng)和后項(xiàng)同時(shí)乘或除以相同的數(shù)（0除外），比值不變。比比與分?jǐn)?shù)、除法之間的聯(lián)系和區(qū)別。比除法分?jǐn)?shù)前項(xiàng)被除數(shù)分子∶（比號(hào)）÷（除號(hào)）—（分?jǐn)?shù)線）后項(xiàng)除數(shù)分母比值商分?jǐn)?shù)值a∶b=a÷b=（b≠0）聯(lián)系比比與分?jǐn)?shù)、除法之間的聯(lián)系和區(qū)別。比表示兩個(gè)量（或數(shù)）的一種關(guān)系，除法是一種運(yùn)算，分?jǐn)?shù)則是一個(gè)數(shù)。區(qū)別化簡(jiǎn)比的方法：

（1）兩個(gè)整數(shù)的比，將前項(xiàng)和后項(xiàng)同時(shí)除以它們的最大公因數(shù)。（2）兩個(gè)分?jǐn)?shù)或小數(shù)的比，先根據(jù)比的基本性質(zhì)將前項(xiàng)和后項(xiàng)都化成整數(shù)，再同時(shí)除以這兩個(gè)整數(shù)的最大公因數(shù)?；?jiǎn)比與求比值的區(qū)別：方法結(jié)果化簡(jiǎn)比求比值根據(jù)比的基本性質(zhì)，將比的前項(xiàng)和后項(xiàng)同時(shí)乘或除以一個(gè)數(shù)用比的前項(xiàng)除以后項(xiàng)一個(gè)最簡(jiǎn)單的整數(shù)比是一個(gè)數(shù)先化簡(jiǎn)下面各比，再求比值。∶0.25=5∶1=53.6∶0.16=45∶2=20∶8=5∶2=表示一個(gè)數(shù)是另一個(gè)數(shù)的百分之幾的數(shù)，叫作百分?jǐn)?shù)。百分?jǐn)?shù)又叫作百分比或百分率。百分?jǐn)?shù)通常不寫成分?jǐn)?shù)形式，而在原來(lái)的分子后面加上百分號(hào)“%”來(lái)表示。64%百分?jǐn)?shù)百分?jǐn)?shù)與分?jǐn)?shù)的聯(lián)系：

百分?jǐn)?shù)是特殊的分?jǐn)?shù)，是兩個(gè)數(shù)量比較的結(jié)果。區(qū)別：①百分?jǐn)?shù)只表示兩個(gè)數(shù)量間的倍比關(guān)系，分?jǐn)?shù)既能表示兩個(gè)數(shù)量間的倍比關(guān)系，又能表示具體數(shù)量。

②百分號(hào)前可以是整數(shù)或小數(shù)，分?jǐn)?shù)的分子分母只能為整數(shù)。64%百分?jǐn)?shù)百分?jǐn)?shù)與比的聯(lián)系：都表示兩個(gè)數(shù)量間的倍比關(guān)系，百分?jǐn)?shù)可以看作后項(xiàng)是100的比。區(qū)別：百分?jǐn)?shù)是一個(gè)數(shù)，比是a∶b的形式。64%百分?jǐn)?shù)小數(shù)改寫成百分?jǐn)?shù)，把小數(shù)點(diǎn)向右移動(dòng)兩位，同時(shí)在后面添上百分號(hào)；百分?jǐn)?shù)改寫成小數(shù)，把百分號(hào)去掉，同時(shí)把小數(shù)點(diǎn)向左移動(dòng)兩位；如果小數(shù)的位數(shù)不夠，用“0”補(bǔ)位。百分?jǐn)?shù)、分?jǐn)?shù)、小數(shù)的改寫分?jǐn)?shù)改寫成百分?jǐn)?shù)，通常要用小數(shù)表示分子除以分母的商，再把商改寫成百分?jǐn)?shù)；計(jì)算中遇到除不盡時(shí)，一般保留三位小數(shù)。還可以把分?jǐn)?shù)改寫成分母是100的分?jǐn)?shù)，再改寫成百分?jǐn)?shù)，但這種方法并不適用于所有分?jǐn)?shù)。百分?jǐn)?shù)、分?jǐn)?shù)、小數(shù)的改寫填表。百分?jǐn)?shù)35%0.5%小數(shù)1.20.045分?jǐn)?shù)120%14.3%4.5%12.5%1.（1）125%==（）∶（）（2）0.45=（）%=（）∶（）=545445920920隨堂演練【選自教