递等式计算,能巧算的要巧算.
630÷6+598
842-462-238
57+43×8
708+247+192
8×78-8×70
67×4÷2.
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解:(1)630÷6+598,
=105+598,
=703;
(2)842-462-238,
=842-(462+238),
=842-700,
=142;
(3)57+43×8,
=57+344,
=401;
(4)708+247+192,
=708+192+247,
=900+247,
=1147;
(5)8×78-8×70,
=(78-70)×8,
=8×8,
=64;
(6)67×4÷2,
=67×(4÷2),
=67×2,
=134.
解析分析:(1)先算除法,再算加法;
(2)根据减法的性质简算;
(3)先算乘法,再算加法;
(4)根据加法交换律简算;
(5)运用乘法分配律简算;
(6)根据乘法结合律简算.
点评:本题考查了四则混合运算,注意运算顺序和运算法则,灵活运用所学的运算定律进行简便计算.