简算4.9+0.1﹣4.9+0.110.78﹣(2.78+3.693)99.99×22.22+33.33×33.34(2.5×2.5+2.5×2.5+2.5×2.5+2.5×2.5)×8.
口算:256800+256600=256000+365500=658900+654200=125600-115600=2560000-1260000=15260000-15160000=
口算:20000+30000=25000+25000=35000+25000=45000-15000=200000-150000=120000-20000=
估算:24560+11260=21410+21210=15610+21000=90410+21060=95230+21245=91210+21260=
估算:705500-50800≈5035433-205000≈305500-108900≈805433+205000≈855500-579900≈533533-205130≈
估算:905500-500900≈403553-205000≈505500-408900≈703543-205050≈803033-205010≈805500-508900≈