Question

10．脫式計算，能簡算的要簡算．
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運用乘法分配律可簡便計算，
②先把3.2分解成4×0.8，再用乘法結(jié)合律簡算，
③先算除法再算減法計算，
④先把3.6分解成0.9×4，再用乘法結(jié)合律簡算，
⑤逆用乘法分配律可簡算，
⑥運用加法交換律和結(jié)合律可簡算．

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

點評 此題考查四則混合運算順序和靈活運用運算定律，分析數(shù)據(jù)找到正確的計算方法．