口算小博士. × = | ÷2= | 80%-20%= | 4×25%+16×25%= |
× = | ×72%= | × ÷ = | × ÷ × = |
× = , | ÷2= , | 80%-20%=0.6, | 4×25%+16×25%=5, |
× = , | ×72%=0.45, | × ÷ = , | × ÷ × = . |
,
,0.6,5,
,0.45,
,
.分析:4×25%+16×25%运用乘法分配律简算;
×
÷
先把除法变成乘法,然后约分求解;
×
÷
×
先把除法变成乘法,再运用乘法结合律简算;其它题目根据运算法则直接求解.点评:本题考查了基本的运算,注意运算法则和运算顺序,灵活运用运算定律简算.
×
÷2=
=
×72%=