【推荐1】直接写出得数．
32+268=________   24×25 =________   640÷40 =________   760-403 =________
28×99 =________   4024÷8=________  45+65+55= ________  174-48-52 =________
420÷35=________  50×15×4=________  68+72=________    460-280=________
230×4 =________  63÷9×7 =________  124-65 =________   360÷4 =________
27+45 =________  46×5-3=________  0×12 =________    125+75 =________

【推荐2】直接写得数．
450÷50=        3×160=        799×41≈   
910÷7=        80×125=        360÷88≈
380×50=       764﹣60=        301÷51≈

【推荐3】先估一估，再写下来
78×6≈________  82×3≈________  631×5≈________ 287×3≈________