解题思路:(1)先算括号内的,再算括号外的除法,最后算加法.
(2)先算小括号内的,再算中括号内的,最后算括号外的.
(3)先算乘法,然后从左往右依次计算.
(4)运用减法的性质简算.
(5)先算括号内的,再算乘法,最后算加法.
(6)先算小括号内的,再算中括号内的除法,然后算中括号内的减法,最后算括号外的乘法.
(1)20.9+10.2÷(5.2-3.5)
=20.9+10.2÷1.7
=20.9+6
=26.9
(2)9.4×[1.28-(1.54-0.31)]
=9.4×[1.28-1.23]
=9.4×0.05
=0.47
(3)10.64+7.65×2.4+11.76
=10.64+18.36+11.76
=(10.64+18.36)+11.76
=29+11.76
=40.76
(4)15.52-4.3-5.7
=15.52-(4.3+5.7)
=15.52-10
=5.52
(5)9.83×(3.8-2.3)+1.5×6.17
=9.83×1.5+9.255
=14.745+9.255
=24
(6)[(6.1-4.6)÷0.8-1]×0.4
=[1.5÷0.8-1]×0.4
=[1.875-1]×0.4
=0.875×0.4
=0.35
点评:
本题考点: 小数四则混合运算.
考点点评: 此题考查了小数的四则混合运算,注意运算顺序和运算法则,灵活运用所学的运算定律简便计算.