四年級(jí)數(shù)學(xué)下冊(cè) 第7章 奇異的克隆?!?shù)加減法 第2課時(shí) 小數(shù)加減混合運(yùn)算課件 青島版六三制.ppt
從圖中,你知道了哪些數(shù)學(xué)信息?,根據(jù)這些信息,你能提出什么問(wèn)題?,“蓓蓓”出生時(shí)的體長(zhǎng)是多少米?,“蓓蓓”百天時(shí)的身高比出生時(shí)增加了多少?,克隆?!拜磔怼鄙砀咔闆r記錄,“蓓蓓”出生時(shí)的體長(zhǎng)是多少米?,你會(huì)解答嗎?試試看。,減加,連減,繼續(xù),百天時(shí)增加0.22米,滿月時(shí)增加0.1米,先算滿月時(shí)體長(zhǎng)是多少米,,“蓓蓓”出生時(shí)的體長(zhǎng)是多少米?,畫線段圖分析:,出生時(shí)體長(zhǎng)?米,再算出生時(shí)體長(zhǎng)多少米。,滿月時(shí)的體長(zhǎng),百天時(shí)的體長(zhǎng)是0.98米,0.980.22=,0.76,(米),0.760.1=,(米),0.66,答:“蓓蓓”出生時(shí)的體長(zhǎng)是0.66米。,返回,百天時(shí)增加0.22米,滿月時(shí)增加0.1米,(),0.22+0.1,先算從出生到百天一共增加了多少米,,=0.98-,“蓓蓓”出生時(shí)的體長(zhǎng)是多少米?,畫線段圖分析:,出生時(shí)體長(zhǎng)?米,0.98,-,=0.66(米),再算出生時(shí)體長(zhǎng)多少米。,先算小括號(hào)里面的,0.32,百天時(shí)的體長(zhǎng)是0.98米,返回,答:“蓓蓓”出生時(shí)的體長(zhǎng)是0.66米。,0.220.1=,0.32,(米),0.980.32=,0.66,(米),還可以寫成:,百天時(shí)增加0.22米,滿月時(shí)增加0.1米,0.22,先算滿月時(shí)體長(zhǎng)是多少米,,“蓓蓓”出生時(shí)的體長(zhǎng)是多少米?,畫線段圖分析:,出生時(shí)體長(zhǎng)?米,0.98,再算出生時(shí)體長(zhǎng)多少米。,滿月時(shí)的體長(zhǎng),百天時(shí)的體長(zhǎng)是0.98米,-,0.1,-,怎樣用一個(gè)豎式計(jì)算連減問(wèn)題呢?,-0.22,怎樣用一個(gè)豎式計(jì)算連減問(wèn)題呢?,0.980.220.1=,0.66(米),0.98,0.76,-0.1,0.66,答:“蓓蓓”出生時(shí)的體長(zhǎng)是0.66米。,返回,9.08,6.04,+2.76,試一試,用豎式計(jì)算。,64.4514.332.19=,17.96,3.28,+3.04,3.28+2.76+3.04=,9.08,17.96,50.15,-14.3,64.45,-32.19,“蓓蓓”百天時(shí)的身高比出生時(shí)增加了多少米?,分步,減加,試一試,你會(huì)解答嗎?試試看。,先算百天時(shí)的身高。,0.81+0.16=,再算百天時(shí)的身高比出生時(shí)增加了多少米。,0.970.78=,0.97,(米),(米),0.19,返回,“蓓蓓”百天時(shí)的身高比出生時(shí)增加了多少米?,答:“蓓蓓”百天時(shí)的身高比出生時(shí)增加了0.19米。,返回,“蓓蓓”百天時(shí)的身高比出生時(shí)增加了多少米?,0.16,0.81,0.78,-,先算百天時(shí)的身高,再算百天時(shí)的身高比出生時(shí)增加了多少米。,+0.16,0.81,0.97,-0.78,0.19,0.19,(米),答:“蓓蓓”百天時(shí)的身高比出生時(shí)增加了0.19米。,16.75,8.22,1.53,試一試,用豎式計(jì)算。,5.833.64.79=,4.64,9.75,+8.53,9.751.538.53=,16.75,4.64,9.43,+3.6,5.83,-4.79,小數(shù)加減混合運(yùn)算的運(yùn)算順序與整數(shù)一樣,從左往右依次計(jì)算,有括號(hào)的先算括號(hào)里面的。,想一想,怎樣計(jì)算小數(shù)加減混合運(yùn)算?,0.980.220.1=,0.66(米),0.16,0.81,0.78,-,0.19(米),0.22+0.1,0.98,-,(),=0.98-,=0.66(米),0.32,這節(jié)課你有哪些收獲?,1.用豎式計(jì)算。,137.35,64.55,-8.25,159(62.39+58)=,38.61,72.8,+72.8,72.8+(72.8-8.25)=,137.35,120.39,+58,62.39,38.61,159,-120.39,4.64,2.,水果區(qū)原有橘子5.83千克,售出4.79千克后,又運(yùn)來(lái)3.6千克?,F(xiàn)在有多少千克橘子?,5.83-4.79+3.6,5.83-4.79,1.04,+3.6,=,答:現(xiàn)在有4.64千克橘子。,4.64(千克),3.,馬的身高是多少米?,2.05,3.62,3.52,-,2.15(米),+2.05,3.62,5.67,-3.52,2.15,答:馬的身高是2.15米,作業(yè),請(qǐng)完成教材第8586頁(yè)自主練習(xí)第3,4,5,6題。,xx小學(xué)x年級(jí)x班,xxx,