问题
解答题
估一估
89×7≈______;312×6≈______;
42×5≈______;297×6≈______;
99×8≈______;319×5≈______.
答案
89×7≈90×7=630;312×6≈310×6=1860;
42×5≈40×5=200; 297×6≈300×6=1800;
99×8≈100×8=800; 319×5≈320×5=1600.
故答案为:630,1860,200,1800,800,1600.