,巧妙估算.302×4≈ 61×2≈ 79×4≈ 290×5≈405×3≈ 385×4≈ 9×820≈ 6×590≈
用竖式计算,并验算.48.5+47.25= ;20.8﹣6.48= .
列竖式计算:3.7+6.05= 8.25﹣4.9= 2.6+12.75= 36×45= 78×22= 87×21=
用竖式进行计算.(带★号的要验算)38.7+1.2=26.04﹣18.9=★63﹣10.17=
列竖式计算.(带☆的写验算)2.4+0.65= 21×43= ☆564÷8= 10.3﹣0.7= 728÷7= 89×46=
列竖式计算下面各题,带△号的要验算.12.7+6.9= 20.5﹣7.6= 78×69=434÷7= 906÷3= △843÷6=验算: