Question

10．脱式计算，能简算的要简算．
102×0.35
0.25×3.2×12.5
3.75÷1.5-0.5
3.6×0.25
0.25×1.2+0.25×2.8
3.5+0.83+0.17+6.5．

Answer 1

分析 ①运用乘法分配律可简便计算，
②先把3.2分解成4×0.8，再用乘法结合律简算，
③先算除法再算减法计算，
④先把3.6分解成0.9×4，再用乘法结合律简算，
⑤逆用乘法分配律可简算，
⑥运用加法交换律和结合律可简算．

解答 解：①102×0.35
=（100+2）×0.35
=100×0.35+2×0.35
=35+0.7
=35.7

②0.25×3.2×12.5
=0.25×（4×0.8）×12.5
=（0.25×4）×（0.8×12.5）
=1×10
=10

③3.75÷1.5-0.5
=2.5-0.5
=2

④3.6×0.25
=（0.9×4）×0.25
=0.9×（4×0.25）
=0.9×1
=0.9

⑤0.25×1.2+0.25×2.8
=0.25×（1.2+2.8）
=0.25×4
=1

⑥3.5+0.83+0.17+6.5
=（3.5+6.5）+（0.83+0.17）
=10+1
=11

点评 此题考查四则混合运算顺序和灵活运用运算定律，分析数据找到正确的计算方法．