考點(diǎn):整數(shù)四則混合運(yùn)算
專題:運(yùn)算順序及法則
分析:(1)先算乘法,再算減法,最后算除法;
(2)先算乘法和除法,再算減法;
(3)先算除法,再算減法,最后算加法;
(4)先算除法,再算減法;
(5)利用加法交換律與減法的性質(zhì)計(jì)算;
(6)先算除法,再算括號(hào)里面的減法,最后算括號(hào)外面的減法.
解答:
解:(1)(166×54-900)÷18
=(8964-900)÷18
=8064÷18
=448;
(2)38×26-1320÷15
=988-88
=900;
(3)400-400÷40+40
=400-10+40
=390+40
=430;
(4)200÷25-1000÷125
=8-8
=0;
(5)2411-643+189-357
=2411+189-(643+357)
=2600-1000
=1600;
(6)100-(3588÷46-78)
=100-(78-78)
=100-0
=100.
點(diǎn)評(píng):整數(shù)混合運(yùn)算的關(guān)鍵是抓住運(yùn)算順序,正確按運(yùn)算順序計(jì)算,適當(dāng)利用運(yùn)算定律簡(jiǎn)算.