估一估.11×8≈ 38×6≈ 58×7≈ 82×3≈289×4≈ 602×6≈ 509×8≈ 511×4≈
口算:15110+21260=35110+22560=52410+21260=120000-115000=256000-156000=6523000-6421000=
估算:675500-510900≈703530-205120≈695540-578905≈503543-105780≈595500-478900≈735433-205540≈
估算:601530-205120≈687240-595905≈512500-145280≈586520-475450≈735433-205540≈595450-471246≈
估算:865500-578900≈803433-205000≈455464-205000≈866546-578900≈70123-105000≈553543-305540≈
口算:831500-554900=25650+21560=95410+21260=1249000-249000=2580010-2580000=246000+154000=