计算(能简算的要简算)
4×8×1.25×25% 37.5%+() 1.8× .
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解:(1)4×8×1.25×25%,
=(4×25%)×(8×1.25),
=1×10,
=10;
(2)37.5%+(),
=+(),
=(+)+,
=1+,
=1;
(3)1.8×,
=(1.8+2.2)×,
=4×,
=1;
(4)×0.3+0.7×0.375,
=0.375×0.3+0.7×0.375,
=0.375×(0.3+0.7),
=0.375×1,
=0.375;
(5)-(2.8+),
=--,
=2-,
=1;
(6),
=2.5×+7.5×,
=(2.5+7.5)×,
=10×,
=3.
解析分析:(1)运用乘法结合律简算;
(2)运用加法交换律简算;
(3)(4)(6)运用乘法分配律简算;
(5)根据减去两个数的和,等于连续减去这两个数简算.
点评:本题考查了简便方法的运用,先观察算式,看符合哪种简算的方法,再由此简算;对于运算定律要熟练掌握.