估算.5.6×9.8≈ 41÷4.9≈ 55.8÷8.02≈36.2÷3.96≈ 0.79×5.02≈ 9.98×5.8≈
笔算下面各题.107×35= 1512÷42=验算 540×18= 3875÷31=验算.
笔算下面各题.358÷49470×56768÷49.
列竖式计算,带★的要验算. 45×36= 403÷8= ★833÷4= 82×17= 870÷3= ★262÷6=
用竖式计算.(带☆的要验算)405×17648÷24816÷51.
计算下面各题并验算. ①802×11 ②329÷48.