Question

【題目】簡便運算：3.85×99； 2.9×101； 1.3×18+1.3×8+1.3×4．

Answer 1

【答案】解：①3.85×99
=3.85×（100﹣1）
=3.85×100﹣3.85
=385﹣3.85
=381.15
②2.9×101
=2.9×（100+1）
=2.9×100+2.9
=290+2.9
=292.9
③1.3×18+1.3×8+1.3×4
=1.3×（18+8+4）
=1.3×30
=39
【解析】考查了運算定律與簡便運算，四則混合運算．注意運算順序和運算法則，靈活運用所學的運算律簡便計算．