竖式计算下列各题。102×4= 209×2=301×3= 504×3=470×2= 307×4=
口算:369500-256900=652000-325600=869500-556900=854000-625600=4512000-4500000=1526000+1574000=
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≈