脱式计算. (80-14)÷6?720-720÷15(360-144)÷24×3240+480÷30×2225-10×(6+13)(120×2+120)÷943×(324-298)(79+21)×(96÷12)
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解:(1)(80-14)÷6,
=66÷6,
=11;
(2)720-720÷15,
=720-48,
=672;
?(3)(360-144)÷24×3,
=216÷24×3,
=9×3,
=27;
(4)240+480÷30×2,
=240+16×2,
=240+32,
=272;
(5)225-10×(6+13),
=225-10×19,
=225-190,
=35;
(6)(120×2+120)÷9,
=(240+120)÷9,
=360÷9,
=40;
(7)43×(324-298),
=43×26,
=1118;
(8)(79+21)×(96÷12),
=100×8,
=800.
解析分析:(1)先算减法,再算除法;(2)先算除法,再算减法;(3)先算减法,再算除法,最后算乘法;(4)先算除法,再算乘法,最后算加法;(5)先算加法,再算乘法,最后算减法;(6)先算乘法,再算加法,最后算除法;(7)先算减法,再算乘法;(8)先算加法和除法,再算乘法.
点评:四则运算,先弄清运算顺序,然后再进一步计算,能简算的要简算.