脫式計(jì)算(能簡(jiǎn)算的要簡(jiǎn)算)
(1)36+59+41+5 (2)372×54+372×46
(3)1462-369-631 (4)3000÷125÷8
(5)48×125 (6)99×63+63
(7)78×102 。8)99×85
(9)118+306÷17+265 。10)540÷45×(65+35)
解:(1)36+59+41+5,
=(36+5)+(59+41),
=41+100,
=141;
(2)372×54+372×46,
=372×(54+46),
=372×100,
=37200;
(3)1462-369-631,
=1462-(369+631),
=1462-1000,
=462;
(4)3000÷125÷8,
=3000÷(125×8),
=3000÷1000,
=3;
(5)48×125,
=125×(8×6),
=(125×8)×6,
=1000×6,
=6000;
(6)99×63+63,
=99×63+1×63,
=63×(99+1),
=63×100,
=6300;
(7)78×102,
=78×(100+2),
=78×100+78×2,
=7800+156,
=7956;
(8)99×85,
=(100-1)×85,
=100×85-1×85,
=8500-85,
=8415;
(9)118+306÷17+265,
=118+18+256,
=136+256,
=392;
(10)540÷45×(65+35),
=540÷45×100,
=540÷(9×5)×100,
=540÷9÷5×100,
=60÷5×100,
=12×100,
=1200.
分析:(1)運(yùn)用加法的交換律、結(jié)合律簡(jiǎn)算;
(2)運(yùn)用乘法分配律簡(jiǎn)算;
(3)根據(jù)連續(xù)減去兩個(gè)數(shù),等于減去這兩個(gè)數(shù)的和簡(jiǎn)算;
(4)根據(jù)連續(xù)除以兩個(gè)數(shù),等于除以這兩個(gè)數(shù)的積簡(jiǎn)算;
(5)把48×125寫(xiě)成125×8×6簡(jiǎn)算;
(6)把99×63+63寫(xiě)成99×63+1×63的形式,運(yùn)用乘法分配律簡(jiǎn)算;
(7)把78×102寫(xiě)成78×(100+2)的形式,運(yùn)用乘法分配律簡(jiǎn)算;
(8)把99×85寫(xiě)成(100-1)×85的形式,運(yùn)用乘法分配律簡(jiǎn)算;
(9)118+306÷17+265 先算除法,再?gòu)淖笙蛴矣?jì)算;
(10)先做小括號(hào)的加法,把45寫(xiě)成9×5,再簡(jiǎn)算.
點(diǎn)評(píng):完成本題要注意分析式中數(shù)據(jù),運(yùn)用合適的簡(jiǎn)便方法計(jì)算.