估算下面各题.89×102≈139×38≈107×42≈41×198≈61×98≈49×102≈
填一填
□﹢76=154 52×□=2236 1365÷□=65 901﹣□=723 □÷30=270 □﹣452=452.
填表.
求横线中的数,并写出计算过程. (1) ×39=2418 (2) ÷26=26 (3) ﹣515=245 (4)72× =360 (5) +192=321 (6)5330÷ =65.
看图写算式. × = ÷ = ÷ = .