问题 解答题 估算.45×29≈32×49≈22×38≈52×68≈69×30≈89×30≈79×20≈42×68≈ 答案 45×29≈1500,32×49≈1500,22×38≈800,52×68≈3500,69×30≈2100,89×30≈2700,79×20≈1600,42×68≈2800.